sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 const unsigned char null_sha1[20];
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 signed char hexval_table[256] = {
  30          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  31          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  32          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  33          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  34          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  35          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  36           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  37           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  38          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  42          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  43          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  44          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  48          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  50          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  51          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  52          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  53          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  54          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  55          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  56          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  57          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  58          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  59          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  60          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  61          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  62 };
  63
  64 int get_sha1_hex(const char *hex, unsigned char *sha1)
  65 {
  66         int i;
  67         for (i = 0; i < 20; i++) {
  68                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  69                 if (val & ~0xff)
  70                         return -1;
  71                 *sha1++ = val;
  72                 hex += 2;
  73         }
  74         return 0;
  75 }
  76
  77 int safe_create_leading_directories(char *path)
  78 {
  79         char *pos = path;
  80         struct stat st;
  81
  82         if (*pos == '/')
  83                 pos++;
  84
  85         while (pos) {
  86                 pos = strchr(pos, '/');
  87                 if (!pos)
  88                         break;
  89                 *pos = 0;
  90                 if (!stat(path, &st)) {
  91                         /* path exists */
  92                         if (!S_ISDIR(st.st_mode)) {
  93                                 *pos = '/';
  94                                 return -3;
  95                         }
  96                 }
  97                 else if (mkdir(path, 0777)) {
  98                         *pos = '/';
  99                         return -1;
 100                 }
 101                 else if (adjust_shared_perm(path)) {
 102                         *pos = '/';
 103                         return -2;
 104                 }
 105                 *pos++ = '/';
 106         }
 107         return 0;
 108 }
 109
 110 char * sha1_to_hex(const unsigned char *sha1)
 111 {
 112         static int bufno;
 113         static char hexbuffer[4][50];
 114         static const char hex[] = "0123456789abcdef";
 115         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 116         int i;
 117
 118         for (i = 0; i < 20; i++) {
 119                 unsigned int val = *sha1++;
 120                 *buf++ = hex[val >> 4];
 121                 *buf++ = hex[val & 0xf];
 122         }
 123         *buf = '\0';
 124
 125         return buffer;
 126 }
 127
 128 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 129 {
 130         int i;
 131         for (i = 0; i < 20; i++) {
 132                 static char hex[] = "0123456789abcdef";
 133                 unsigned int val = sha1[i];
 134                 char *pos = pathbuf + i*2 + (i > 0);
 135                 *pos++ = hex[val >> 4];
 136                 *pos = hex[val & 0xf];
 137         }
 138 }
 139
 140 /*
 141  * NOTE! This returns a statically allocated buffer, so you have to be
 142  * careful about using it. Do a "xstrdup()" if you need to save the
 143  * filename.
 144  *
 145  * Also note that this returns the location for creating.  Reading
 146  * SHA1 file can happen from any alternate directory listed in the
 147  * DB_ENVIRONMENT environment variable if it is not found in
 148  * the primary object database.
 149  */
 150 char *sha1_file_name(const unsigned char *sha1)
 151 {
 152         static char *name, *base;
 153
 154         if (!base) {
 155                 const char *sha1_file_directory = get_object_directory();
 156                 int len = strlen(sha1_file_directory);
 157                 base = xmalloc(len + 60);
 158                 memcpy(base, sha1_file_directory, len);
 159                 memset(base+len, 0, 60);
 160                 base[len] = '/';
 161                 base[len+3] = '/';
 162                 name = base + len + 1;
 163         }
 164         fill_sha1_path(name, sha1);
 165         return base;
 166 }
 167
 168 char *sha1_pack_name(const unsigned char *sha1)
 169 {
 170         static const char hex[] = "0123456789abcdef";
 171         static char *name, *base, *buf;
 172         int i;
 173
 174         if (!base) {
 175                 const char *sha1_file_directory = get_object_directory();
 176                 int len = strlen(sha1_file_directory);
 177                 base = xmalloc(len + 60);
 178                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 179                 name = base + len + 11;
 180         }
 181
 182         buf = name;
 183
 184         for (i = 0; i < 20; i++) {
 185                 unsigned int val = *sha1++;
 186                 *buf++ = hex[val >> 4];
 187                 *buf++ = hex[val & 0xf];
 188         }
 189
 190         return base;
 191 }
 192
 193 char *sha1_pack_index_name(const unsigned char *sha1)
 194 {
 195         static const char hex[] = "0123456789abcdef";
 196         static char *name, *base, *buf;
 197         int i;
 198
 199         if (!base) {
 200                 const char *sha1_file_directory = get_object_directory();
 201                 int len = strlen(sha1_file_directory);
 202                 base = xmalloc(len + 60);
 203                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 204                 name = base + len + 11;
 205         }
 206
 207         buf = name;
 208
 209         for (i = 0; i < 20; i++) {
 210                 unsigned int val = *sha1++;
 211                 *buf++ = hex[val >> 4];
 212                 *buf++ = hex[val & 0xf];
 213         }
 214
 215         return base;
 216 }
 217
 218 struct alternate_object_database *alt_odb_list;
 219 static struct alternate_object_database **alt_odb_tail;
 220
 221 static void read_info_alternates(const char * alternates, int depth);
 222
 223 /*
 224  * Prepare alternate object database registry.
 225  *
 226  * The variable alt_odb_list points at the list of struct
 227  * alternate_object_database.  The elements on this list come from
 228  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 229  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 230  * whose contents is similar to that environment variable but can be
 231  * LF separated.  Its base points at a statically allocated buffer that
 232  * contains "/the/directory/corresponding/to/.git/objects/...", while
 233  * its name points just after the slash at the end of ".git/objects/"
 234  * in the example above, and has enough space to hold 40-byte hex
 235  * SHA1, an extra slash for the first level indirection, and the
 236  * terminating NUL.
 237  */
 238 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 239 {
 240         struct stat st;
 241         const char *objdir = get_object_directory();
 242         struct alternate_object_database *ent;
 243         struct alternate_object_database *alt;
 244         /* 43 = 40-byte + 2 '/' + terminating NUL */
 245         int pfxlen = len;
 246         int entlen = pfxlen + 43;
 247         int base_len = -1;
 248
 249         if (*entry != '/' && relative_base) {
 250                 /* Relative alt-odb */
 251                 if (base_len < 0)
 252                         base_len = strlen(relative_base) + 1;
 253                 entlen += base_len;
 254                 pfxlen += base_len;
 255         }
 256         ent = xmalloc(sizeof(*ent) + entlen);
 257
 258         if (*entry != '/' && relative_base) {
 259                 memcpy(ent->base, relative_base, base_len - 1);
 260                 ent->base[base_len - 1] = '/';
 261                 memcpy(ent->base + base_len, entry, len);
 262         }
 263         else
 264                 memcpy(ent->base, entry, pfxlen);
 265
 266         ent->name = ent->base + pfxlen + 1;
 267         ent->base[pfxlen + 3] = '/';
 268         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 269
 270         /* Detect cases where alternate disappeared */
 271         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 272                 error("object directory %s does not exist; "
 273                       "check .git/objects/info/alternates.",
 274                       ent->base);
 275                 free(ent);
 276                 return -1;
 277         }
 278
 279         /* Prevent the common mistake of listing the same
 280          * thing twice, or object directory itself.
 281          */
 282         for (alt = alt_odb_list; alt; alt = alt->next) {
 283                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 284                         free(ent);
 285                         return -1;
 286                 }
 287         }
 288         if (!memcmp(ent->base, objdir, pfxlen)) {
 289                 free(ent);
 290                 return -1;
 291         }
 292
 293         /* add the alternate entry */
 294         *alt_odb_tail = ent;
 295         alt_odb_tail = &(ent->next);
 296         ent->next = NULL;
 297
 298         /* recursively add alternates */
 299         read_info_alternates(ent->base, depth + 1);
 300
 301         ent->base[pfxlen] = '/';
 302
 303         return 0;
 304 }
 305
 306 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 307                                  const char *relative_base, int depth)
 308 {
 309         const char *cp, *last;
 310
 311         if (depth > 5) {
 312                 error("%s: ignoring alternate object stores, nesting too deep.",
 313                                 relative_base);
 314                 return;
 315         }
 316
 317         last = alt;
 318         while (last < ep) {
 319                 cp = last;
 320                 if (cp < ep && *cp == '#') {
 321                         while (cp < ep && *cp != sep)
 322                                 cp++;
 323                         last = cp + 1;
 324                         continue;
 325                 }
 326                 while (cp < ep && *cp != sep)
 327                         cp++;
 328                 if (last != cp) {
 329                         if ((*last != '/') && depth) {
 330                                 error("%s: ignoring relative alternate object store %s",
 331                                                 relative_base, last);
 332                         } else {
 333                                 link_alt_odb_entry(last, cp - last,
 334                                                 relative_base, depth);
 335                         }
 336                 }
 337                 while (cp < ep && *cp == sep)
 338                         cp++;
 339                 last = cp;
 340         }
 341 }
 342
 343 static void read_info_alternates(const char * relative_base, int depth)
 344 {
 345         char *map;
 346         struct stat st;
 347         char path[PATH_MAX];
 348         int fd;
 349
 350         sprintf(path, "%s/info/alternates", relative_base);
 351         fd = open(path, O_RDONLY);
 352         if (fd < 0)
 353                 return;
 354         if (fstat(fd, &st) || (st.st_size == 0)) {
 355                 close(fd);
 356                 return;
 357         }
 358         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 359         close(fd);
 360         if (map == MAP_FAILED)
 361                 return;
 362
 363         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 364
 365         munmap(map, st.st_size);
 366 }
 367
 368 void prepare_alt_odb(void)
 369 {
 370         const char *alt;
 371
 372         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 373         if (!alt) alt = "";
 374
 375         if (alt_odb_tail)
 376                 return;
 377         alt_odb_tail = &alt_odb_list;
 378         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 379
 380         read_info_alternates(get_object_directory(), 0);
 381 }
 382
 383 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 384 {
 385         char *name = sha1_file_name(sha1);
 386         struct alternate_object_database *alt;
 387
 388         if (!stat(name, st))
 389                 return name;
 390         prepare_alt_odb();
 391         for (alt = alt_odb_list; alt; alt = alt->next) {
 392                 name = alt->name;
 393                 fill_sha1_path(name, sha1);
 394                 if (!stat(alt->base, st))
 395                         return alt->base;
 396         }
 397         return NULL;
 398 }
 399
 400 static unsigned int pack_used_ctr;
 401 static size_t pack_mapped;
 402 static size_t page_size;
 403 struct packed_git *packed_git;
 404
 405 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 406                                 void **idx_map_)
 407 {
 408         void *idx_map;
 409         unsigned int *index;
 410         unsigned long idx_size;
 411         int nr, i;
 412         int fd = open(path, O_RDONLY);
 413         struct stat st;
 414         if (fd < 0)
 415                 return -1;
 416         if (fstat(fd, &st)) {
 417                 close(fd);
 418                 return -1;
 419         }
 420         idx_size = st.st_size;
 421         idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 422         close(fd);
 423         if (idx_map == MAP_FAILED)
 424                 return -1;
 425
 426         index = idx_map;
 427         *idx_map_ = idx_map;
 428         *idx_size_ = idx_size;
 429
 430         /* check index map */
 431         if (idx_size < 4*256 + 20 + 20)
 432                 return error("index file too small");
 433         nr = 0;
 434         for (i = 0; i < 256; i++) {
 435                 unsigned int n = ntohl(index[i]);
 436                 if (n < nr)
 437                         return error("non-monotonic index");
 438                 nr = n;
 439         }
 440
 441         /*
 442          * Total size:
 443          *  - 256 index entries 4 bytes each
 444          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 445          *  - 20-byte SHA1 of the packfile
 446          *  - 20-byte SHA1 file checksum
 447          */
 448         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 449                 return error("wrong index file size");
 450
 451         return 0;
 452 }
 453
 454 static void scan_windows(struct packed_git *p,
 455         struct packed_git **lru_p,
 456         struct pack_window **lru_w,
 457         struct pack_window **lru_l)
 458 {
 459         struct pack_window *w, *w_l;
 460
 461         for (w_l = NULL, w = p->windows; w; w = w->next) {
 462                 if (!w->inuse_cnt) {
 463                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 464                                 *lru_p = p;
 465                                 *lru_w = w;
 466                                 *lru_l = w_l;
 467                         }
 468                 }
 469                 w_l = w;
 470         }
 471 }
 472
 473 static int unuse_one_window(struct packed_git *current)
 474 {
 475         struct packed_git *p, *lru_p = NULL;
 476         struct pack_window *lru_w = NULL, *lru_l = NULL;
 477
 478         if (current)
 479                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 480         for (p = packed_git; p; p = p->next)
 481                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 482         if (lru_p) {
 483                 munmap(lru_w->base, lru_w->len);
 484                 pack_mapped -= lru_w->len;
 485                 if (lru_l)
 486                         lru_l->next = lru_w->next;
 487                 else {
 488                         lru_p->windows = lru_w->next;
 489                         if (!lru_p->windows && lru_p != current) {
 490                                 close(lru_p->pack_fd);
 491                                 lru_p->pack_fd = -1;
 492                         }
 493                 }
 494                 free(lru_w);
 495                 return 1;
 496         }
 497         return 0;
 498 }
 499
 500 void unuse_pack(struct pack_window **w_cursor)
 501 {
 502         struct pack_window *w = *w_cursor;
 503         if (w) {
 504                 w->inuse_cnt--;
 505                 *w_cursor = NULL;
 506         }
 507 }
 508
 509 static void open_packed_git(struct packed_git *p)
 510 {
 511         struct stat st;
 512         struct pack_header hdr;
 513         unsigned char sha1[20];
 514         unsigned char *idx_sha1;
 515
 516         p->pack_fd = open(p->pack_name, O_RDONLY);
 517         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 518                 die("packfile %s cannot be opened", p->pack_name);
 519
 520         /* If we created the struct before we had the pack we lack size. */
 521         if (!p->pack_size) {
 522                 if (!S_ISREG(st.st_mode))
 523                         die("packfile %s not a regular file", p->pack_name);
 524                 p->pack_size = st.st_size;
 525         } else if (p->pack_size != st.st_size)
 526                 die("packfile %s size changed", p->pack_name);
 527
 528         /* Verify we recognize this pack file format. */
 529         read_or_die(p->pack_fd, &hdr, sizeof(hdr));
 530         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 531                 die("file %s is not a GIT packfile", p->pack_name);
 532         if (!pack_version_ok(hdr.hdr_version))
 533                 die("packfile %s is version %u and not supported"
 534                         " (try upgrading GIT to a newer version)",
 535                         p->pack_name, ntohl(hdr.hdr_version));
 536
 537         /* Verify the pack matches its index. */
 538         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 539                 die("packfile %s claims to have %u objects"
 540                         " while index size indicates %u objects",
 541                         p->pack_name, ntohl(hdr.hdr_entries),
 542                         num_packed_objects(p));
 543         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 544                 die("end of packfile %s is unavailable", p->pack_name);
 545         read_or_die(p->pack_fd, sha1, sizeof(sha1));
 546         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 547         if (hashcmp(sha1, idx_sha1))
 548                 die("packfile %s does not match index", p->pack_name);
 549 }
 550
 551 static int in_window(struct pack_window *win, unsigned long offset)
 552 {
 553         /* We must promise at least 20 bytes (one hash) after the
 554          * offset is available from this window, otherwise the offset
 555          * is not actually in this window and a different window (which
 556          * has that one hash excess) must be used.  This is to support
 557          * the object header and delta base parsing routines below.
 558          */
 559         off_t win_off = win->offset;
 560         return win_off <= offset
 561                 && (offset + 20) <= (win_off + win->len);
 562 }
 563
 564 unsigned char* use_pack(struct packed_git *p,
 565                 struct pack_window **w_cursor,
 566                 unsigned long offset,
 567                 unsigned int *left)
 568 {
 569         struct pack_window *win = *w_cursor;
 570
 571         if (p->pack_fd == -1)
 572                 open_packed_git(p);
 573
 574         /* Since packfiles end in a hash of their content and its
 575          * pointless to ask for an offset into the middle of that
 576          * hash, and the in_window function above wouldn't match
 577          * don't allow an offset too close to the end of the file.
 578          */
 579         if (offset > (p->pack_size - 20))
 580                 die("offset beyond end of packfile (truncated pack?)");
 581
 582         if (!win || !in_window(win, offset)) {
 583                 if (win)
 584                         win->inuse_cnt--;
 585                 for (win = p->windows; win; win = win->next) {
 586                         if (in_window(win, offset))
 587                                 break;
 588                 }
 589                 if (!win) {
 590                         if (!page_size)
 591                                 page_size = getpagesize();
 592                         win = xcalloc(1, sizeof(*win));
 593                         win->offset = (offset / page_size) * page_size;
 594                         win->len = p->pack_size - win->offset;
 595                         if (win->len > packed_git_window_size)
 596                                 win->len = packed_git_window_size;
 597                         pack_mapped += win->len;
 598                         while (packed_git_limit < pack_mapped
 599                                 && unuse_one_window(p))
 600                                 ; /* nothing */
 601                         win->base = mmap(NULL, win->len,
 602                                 PROT_READ, MAP_PRIVATE,
 603                                 p->pack_fd, win->offset);
 604                         if (win->base == MAP_FAILED)
 605                                 die("packfile %s cannot be mapped: %s",
 606                                         p->pack_name,
 607                                         strerror(errno));
 608                         win->next = p->windows;
 609                         p->windows = win;
 610                 }
 611         }
 612         if (win != *w_cursor) {
 613                 win->last_used = pack_used_ctr++;
 614                 win->inuse_cnt++;
 615                 *w_cursor = win;
 616         }
 617         offset -= win->offset;
 618         if (left)
 619                 *left = win->len - offset;
 620         return win->base + offset;
 621 }
 622
 623 struct packed_git *add_packed_git(char *path, int path_len, int local)
 624 {
 625         struct stat st;
 626         struct packed_git *p;
 627         unsigned long idx_size;
 628         void *idx_map;
 629         unsigned char sha1[20];
 630
 631         if (check_packed_git_idx(path, &idx_size, &idx_map))
 632                 return NULL;
 633
 634         /* do we have a corresponding .pack file? */
 635         strcpy(path + path_len - 4, ".pack");
 636         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 637                 munmap(idx_map, idx_size);
 638                 return NULL;
 639         }
 640         /* ok, it looks sane as far as we can check without
 641          * actually mapping the pack file.
 642          */
 643         p = xmalloc(sizeof(*p) + path_len + 2);
 644         strcpy(p->pack_name, path);
 645         p->index_size = idx_size;
 646         p->pack_size = st.st_size;
 647         p->index_base = idx_map;
 648         p->next = NULL;
 649         p->windows = NULL;
 650         p->pack_fd = -1;
 651         p->pack_local = local;
 652         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 653                 hashcpy(p->sha1, sha1);
 654         return p;
 655 }
 656
 657 struct packed_git *parse_pack_index(unsigned char *sha1)
 658 {
 659         char *path = sha1_pack_index_name(sha1);
 660         return parse_pack_index_file(sha1, path);
 661 }
 662
 663 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 664 {
 665         struct packed_git *p;
 666         unsigned long idx_size;
 667         void *idx_map;
 668         char *path;
 669
 670         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 671                 return NULL;
 672
 673         path = sha1_pack_name(sha1);
 674
 675         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 676         strcpy(p->pack_name, path);
 677         p->index_size = idx_size;
 678         p->pack_size = 0;
 679         p->index_base = idx_map;
 680         p->next = NULL;
 681         p->windows = NULL;
 682         p->pack_fd = -1;
 683         hashcpy(p->sha1, sha1);
 684         return p;
 685 }
 686
 687 void install_packed_git(struct packed_git *pack)
 688 {
 689         pack->next = packed_git;
 690         packed_git = pack;
 691 }
 692
 693 static void prepare_packed_git_one(char *objdir, int local)
 694 {
 695         char path[PATH_MAX];
 696         int len;
 697         DIR *dir;
 698         struct dirent *de;
 699
 700         sprintf(path, "%s/pack", objdir);
 701         len = strlen(path);
 702         dir = opendir(path);
 703         if (!dir) {
 704                 if (errno != ENOENT)
 705                         error("unable to open object pack directory: %s: %s",
 706                               path, strerror(errno));
 707                 return;
 708         }
 709         path[len++] = '/';
 710         while ((de = readdir(dir)) != NULL) {
 711                 int namelen = strlen(de->d_name);
 712                 struct packed_git *p;
 713
 714                 if (!has_extension(de->d_name, ".idx"))
 715                         continue;
 716
 717                 /* we have .idx.  Is it a file we can map? */
 718                 strcpy(path + len, de->d_name);
 719                 for (p = packed_git; p; p = p->next) {
 720                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 721                                 break;
 722                 }
 723                 if (p)
 724                         continue;
 725                 p = add_packed_git(path, len + namelen, local);
 726                 if (!p)
 727                         continue;
 728                 p->next = packed_git;
 729                 packed_git = p;
 730         }
 731         closedir(dir);
 732 }
 733
 734 static int prepare_packed_git_run_once = 0;
 735 void prepare_packed_git(void)
 736 {
 737         struct alternate_object_database *alt;
 738
 739         if (prepare_packed_git_run_once)
 740                 return;
 741         prepare_packed_git_one(get_object_directory(), 1);
 742         prepare_alt_odb();
 743         for (alt = alt_odb_list; alt; alt = alt->next) {
 744                 alt->name[-1] = 0;
 745                 prepare_packed_git_one(alt->base, 0);
 746                 alt->name[-1] = '/';
 747         }
 748         prepare_packed_git_run_once = 1;
 749 }
 750
 751 void reprepare_packed_git(void)
 752 {
 753         prepare_packed_git_run_once = 0;
 754         prepare_packed_git();
 755 }
 756
 757 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 758 {
 759         unsigned char real_sha1[20];
 760         hash_sha1_file(map, size, type, real_sha1);
 761         return hashcmp(sha1, real_sha1) ? -1 : 0;
 762 }
 763
 764 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 765 {
 766         struct stat st;
 767         void *map;
 768         int fd;
 769         char *filename = find_sha1_file(sha1, &st);
 770
 771         if (!filename) {
 772                 return NULL;
 773         }
 774
 775         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 776         if (fd < 0) {
 777                 /* See if it works without O_NOATIME */
 778                 switch (sha1_file_open_flag) {
 779                 default:
 780                         fd = open(filename, O_RDONLY);
 781                         if (fd >= 0)
 782                                 break;
 783                 /* Fallthrough */
 784                 case 0:
 785                         return NULL;
 786                 }
 787
 788                 /* If it failed once, it will probably fail again.
 789                  * Stop using O_NOATIME
 790                  */
 791                 sha1_file_open_flag = 0;
 792         }
 793         map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 794         close(fd);
 795         if (map == MAP_FAILED)
 796                 return NULL;
 797         *size = st.st_size;
 798         return map;
 799 }
 800
 801 int legacy_loose_object(unsigned char *map)
 802 {
 803         unsigned int word;
 804
 805         /*
 806          * Is it a zlib-compressed buffer? If so, the first byte
 807          * must be 0x78 (15-bit window size, deflated), and the
 808          * first 16-bit word is evenly divisible by 31
 809          */
 810         word = (map[0] << 8) + map[1];
 811         if (map[0] == 0x78 && !(word % 31))
 812                 return 1;
 813         else
 814                 return 0;
 815 }
 816
 817 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 818 {
 819         unsigned shift;
 820         unsigned char c;
 821         unsigned long size;
 822         unsigned long used = 0;
 823
 824         c = buf[used++];
 825         *type = (c >> 4) & 7;
 826         size = c & 15;
 827         shift = 4;
 828         while (c & 0x80) {
 829                 if (len <= used)
 830                         return 0;
 831                 if (sizeof(long) * 8 <= shift)
 832                         return 0;
 833                 c = buf[used++];
 834                 size += (c & 0x7f) << shift;
 835                 shift += 7;
 836         }
 837         *sizep = size;
 838         return used;
 839 }
 840
 841 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 842 {
 843         unsigned long size, used;
 844         static const char valid_loose_object_type[8] = {
 845                 0, /* OBJ_EXT */
 846                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 847                 0, /* "delta" and others are invalid in a loose object */
 848         };
 849         enum object_type type;
 850
 851         /* Get the data stream */
 852         memset(stream, 0, sizeof(*stream));
 853         stream->next_in = map;
 854         stream->avail_in = mapsize;
 855         stream->next_out = buffer;
 856         stream->avail_out = bufsiz;
 857
 858         if (legacy_loose_object(map)) {
 859                 inflateInit(stream);
 860                 return inflate(stream, 0);
 861         }
 862
 863         used = unpack_object_header_gently(map, mapsize, &type, &size);
 864         if (!used || !valid_loose_object_type[type])
 865                 return -1;
 866         map += used;
 867         mapsize -= used;
 868
 869         /* Set up the stream for the rest.. */
 870         stream->next_in = map;
 871         stream->avail_in = mapsize;
 872         inflateInit(stream);
 873
 874         /* And generate the fake traditional header */
 875         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 876                                          type_names[type], size);
 877         return 0;
 878 }
 879
 880 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 881 {
 882         int bytes = strlen(buffer) + 1;
 883         unsigned char *buf = xmalloc(1+size);
 884         unsigned long n;
 885
 886         n = stream->total_out - bytes;
 887         if (n > size)
 888                 n = size;
 889         memcpy(buf, (char *) buffer + bytes, n);
 890         bytes = n;
 891         if (bytes < size) {
 892                 stream->next_out = buf + bytes;
 893                 stream->avail_out = size - bytes;
 894                 while (inflate(stream, Z_FINISH) == Z_OK)
 895                         /* nothing */;
 896         }
 897         buf[size] = 0;
 898         inflateEnd(stream);
 899         return buf;
 900 }
 901
 902 /*
 903  * We used to just use "sscanf()", but that's actually way
 904  * too permissive for what we want to check. So do an anal
 905  * object header parse by hand.
 906  */
 907 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 908 {
 909         int i;
 910         unsigned long size;
 911
 912         /*
 913          * The type can be at most ten bytes (including the
 914          * terminating '\0' that we add), and is followed by
 915          * a space.
 916          */
 917         i = 10;
 918         for (;;) {
 919                 char c = *hdr++;
 920                 if (c == ' ')
 921                         break;
 922                 if (!--i)
 923                         return -1;
 924                 *type++ = c;
 925         }
 926         *type = 0;
 927
 928         /*
 929          * The length must follow immediately, and be in canonical
 930          * decimal format (ie "010" is not valid).
 931          */
 932         size = *hdr++ - '0';
 933         if (size > 9)
 934                 return -1;
 935         if (size) {
 936                 for (;;) {
 937                         unsigned long c = *hdr - '0';
 938                         if (c > 9)
 939                                 break;
 940                         hdr++;
 941                         size = size * 10 + c;
 942                 }
 943         }
 944         *sizep = size;
 945
 946         /*
 947          * The length must be followed by a zero byte
 948          */
 949         return *hdr ? -1 : 0;
 950 }
 951
 952 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 953 {
 954         int ret;
 955         z_stream stream;
 956         char hdr[8192];
 957
 958         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 959         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 960                 return NULL;
 961
 962         return unpack_sha1_rest(&stream, hdr, *size);
 963 }
 964
 965 static unsigned long get_delta_base(struct packed_git *p,
 966                                     struct pack_window **w_curs,
 967                                     unsigned long offset,
 968                                     enum object_type kind,
 969                                     unsigned long delta_obj_offset,
 970                                     unsigned long *base_obj_offset)
 971 {
 972         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
 973         unsigned long base_offset;
 974
 975         /* use_pack() assured us we have [base_info, base_info + 20)
 976          * as a range that we can look at without walking off the
 977          * end of the mapped window.  Its actually the hash size
 978          * that is assured.  An OFS_DELTA longer than the hash size
 979          * is stupid, as then a REF_DELTA would be smaller to store.
 980          */
 981         if (kind == OBJ_OFS_DELTA) {
 982                 unsigned used = 0;
 983                 unsigned char c = base_info[used++];
 984                 base_offset = c & 127;
 985                 while (c & 128) {
 986                         base_offset += 1;
 987                         if (!base_offset || base_offset & ~(~0UL >> 7))
 988                                 die("offset value overflow for delta base object");
 989                         c = base_info[used++];
 990                         base_offset = (base_offset << 7) + (c & 127);
 991                 }
 992                 base_offset = delta_obj_offset - base_offset;
 993                 if (base_offset >= delta_obj_offset)
 994                         die("delta base offset out of bound");
 995                 offset += used;
 996         } else if (kind == OBJ_REF_DELTA) {
 997                 /* The base entry _must_ be in the same pack */
 998                 base_offset = find_pack_entry_one(base_info, p);
 999                 if (!base_offset)
1000                         die("failed to find delta-pack base object %s",
1001                                 sha1_to_hex(base_info));
1002                 offset += 20;
1003         } else
1004                 die("I am totally screwed");
1005         *base_obj_offset = base_offset;
1006         return offset;
1007 }
1008
1009 /* forward declaration for a mutually recursive function */
1010 static int packed_object_info(struct packed_git *p, unsigned long offset,
1011                               char *type, unsigned long *sizep);
1012
1013 static int packed_delta_info(struct packed_git *p,
1014                              struct pack_window **w_curs,
1015                              unsigned long offset,
1016                              enum object_type kind,
1017                              unsigned long obj_offset,
1018                              char *type,
1019                              unsigned long *sizep)
1020 {
1021         unsigned long base_offset;
1022
1023         offset = get_delta_base(p, w_curs, offset, kind,
1024                 obj_offset, &base_offset);
1025
1026         /* We choose to only get the type of the base object and
1027          * ignore potentially corrupt pack file that expects the delta
1028          * based on a base with a wrong size.  This saves tons of
1029          * inflate() calls.
1030          */
1031         if (packed_object_info(p, base_offset, type, NULL))
1032                 die("cannot get info for delta-pack base");
1033
1034         if (sizep) {
1035                 const unsigned char *data;
1036                 unsigned char delta_head[20], *in;
1037                 unsigned long result_size;
1038                 z_stream stream;
1039                 int st;
1040
1041                 memset(&stream, 0, sizeof(stream));
1042                 stream.next_out = delta_head;
1043                 stream.avail_out = sizeof(delta_head);
1044
1045                 inflateInit(&stream);
1046                 do {
1047                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1048                         stream.next_in = in;
1049                         st = inflate(&stream, Z_FINISH);
1050                         offset += stream.next_in - in;
1051                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1052                         && stream.total_out < sizeof(delta_head));
1053                 inflateEnd(&stream);
1054                 if ((st != Z_STREAM_END) &&
1055                     stream.total_out != sizeof(delta_head))
1056                         die("delta data unpack-initial failed");
1057
1058                 /* Examine the initial part of the delta to figure out
1059                  * the result size.
1060                  */
1061                 data = delta_head;
1062
1063                 /* ignore base size */
1064                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1065
1066                 /* Read the result size */
1067                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1068                 *sizep = result_size;
1069         }
1070         return 0;
1071 }
1072
1073 static unsigned long unpack_object_header(struct packed_git *p,
1074                 struct pack_window **w_curs,
1075                 unsigned long offset,
1076                 enum object_type *type,
1077                 unsigned long *sizep)
1078 {
1079         unsigned char *base;
1080         unsigned int left;
1081         unsigned long used;
1082
1083         /* use_pack() assures us we have [base, base + 20) available
1084          * as a range that we can look at at.  (Its actually the hash
1085          * size that is assurred.)  With our object header encoding
1086          * the maximum deflated object size is 2^137, which is just
1087          * insane, so we know won't exceed what we have been given.
1088          */
1089         base = use_pack(p, w_curs, offset, &left);
1090         used = unpack_object_header_gently(base, left, type, sizep);
1091         if (!used)
1092                 die("object offset outside of pack file");
1093
1094         return offset + used;
1095 }
1096
1097 void packed_object_info_detail(struct packed_git *p,
1098                                unsigned long offset,
1099                                char *type,
1100                                unsigned long *size,
1101                                unsigned long *store_size,
1102                                unsigned int *delta_chain_length,
1103                                unsigned char *base_sha1)
1104 {
1105         struct pack_window *w_curs = NULL;
1106         unsigned long obj_offset, val;
1107         unsigned char *next_sha1;
1108         enum object_type kind;
1109
1110         *delta_chain_length = 0;
1111         obj_offset = offset;
1112         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1113
1114         for (;;) {
1115                 switch (kind) {
1116                 default:
1117                         die("pack %s contains unknown object type %d",
1118                             p->pack_name, kind);
1119                 case OBJ_COMMIT:
1120                 case OBJ_TREE:
1121                 case OBJ_BLOB:
1122                 case OBJ_TAG:
1123                         strcpy(type, type_names[kind]);
1124                         *store_size = 0; /* notyet */
1125                         unuse_pack(&w_curs);
1126                         return;
1127                 case OBJ_OFS_DELTA:
1128                         get_delta_base(p, &w_curs, offset, kind,
1129                                 obj_offset, &offset);
1130                         if (*delta_chain_length == 0) {
1131                                 /* TODO: find base_sha1 as pointed by offset */
1132                         }
1133                         break;
1134                 case OBJ_REF_DELTA:
1135                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1136                         if (*delta_chain_length == 0)
1137                                 hashcpy(base_sha1, next_sha1);
1138                         offset = find_pack_entry_one(next_sha1, p);
1139                         break;
1140                 }
1141                 obj_offset = offset;
1142                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1143                 (*delta_chain_length)++;
1144         }
1145 }
1146
1147 static int packed_object_info(struct packed_git *p, unsigned long offset,
1148                               char *type, unsigned long *sizep)
1149 {
1150         struct pack_window *w_curs = NULL;
1151         unsigned long size, obj_offset = offset;
1152         enum object_type kind;
1153         int r;
1154
1155         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1156
1157         switch (kind) {
1158         case OBJ_OFS_DELTA:
1159         case OBJ_REF_DELTA:
1160                 r = packed_delta_info(p, &w_curs, offset, kind,
1161                         obj_offset, type, sizep);
1162                 unuse_pack(&w_curs);
1163                 return r;
1164         case OBJ_COMMIT:
1165         case OBJ_TREE:
1166         case OBJ_BLOB:
1167         case OBJ_TAG:
1168                 strcpy(type, type_names[kind]);
1169                 unuse_pack(&w_curs);
1170                 break;
1171         default:
1172                 die("pack %s contains unknown object type %d",
1173                     p->pack_name, kind);
1174         }
1175         if (sizep)
1176                 *sizep = size;
1177         return 0;
1178 }
1179
1180 static void *unpack_compressed_entry(struct packed_git *p,
1181                                     struct pack_window **w_curs,
1182                                     unsigned long offset,
1183                                     unsigned long size)
1184 {
1185         int st;
1186         z_stream stream;
1187         unsigned char *buffer, *in;
1188
1189         buffer = xmalloc(size + 1);
1190         buffer[size] = 0;
1191         memset(&stream, 0, sizeof(stream));
1192         stream.next_out = buffer;
1193         stream.avail_out = size;
1194
1195         inflateInit(&stream);
1196         do {
1197                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1198                 stream.next_in = in;
1199                 st = inflate(&stream, Z_FINISH);
1200                 offset += stream.next_in - in;
1201         } while (st == Z_OK || st == Z_BUF_ERROR);
1202         inflateEnd(&stream);
1203         if ((st != Z_STREAM_END) || stream.total_out != size) {
1204                 free(buffer);
1205                 return NULL;
1206         }
1207
1208         return buffer;
1209 }
1210
1211 static void *unpack_delta_entry(struct packed_git *p,
1212                                 struct pack_window **w_curs,
1213                                 unsigned long offset,
1214                                 unsigned long delta_size,
1215                                 enum object_type kind,
1216                                 unsigned long obj_offset,
1217                                 char *type,
1218                                 unsigned long *sizep)
1219 {
1220         void *delta_data, *result, *base;
1221         unsigned long result_size, base_size, base_offset;
1222
1223         offset = get_delta_base(p, w_curs, offset, kind,
1224                 obj_offset, &base_offset);
1225         base = unpack_entry(p, base_offset, type, &base_size);
1226         if (!base)
1227                 die("failed to read delta base object at %lu from %s",
1228                     base_offset, p->pack_name);
1229
1230         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1231         result = patch_delta(base, base_size,
1232                              delta_data, delta_size,
1233                              &result_size);
1234         if (!result)
1235                 die("failed to apply delta");
1236         free(delta_data);
1237         free(base);
1238         *sizep = result_size;
1239         return result;
1240 }
1241
1242 void *unpack_entry(struct packed_git *p, unsigned long offset,
1243                           char *type, unsigned long *sizep)
1244 {
1245         struct pack_window *w_curs = NULL;
1246         unsigned long size, obj_offset = offset;
1247         enum object_type kind;
1248         void *retval;
1249
1250         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1251         switch (kind) {
1252         case OBJ_OFS_DELTA:
1253         case OBJ_REF_DELTA:
1254                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1255                         kind, obj_offset, type, sizep);
1256                 break;
1257         case OBJ_COMMIT:
1258         case OBJ_TREE:
1259         case OBJ_BLOB:
1260         case OBJ_TAG:
1261                 strcpy(type, type_names[kind]);
1262                 *sizep = size;
1263                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1264                 break;
1265         default:
1266                 die("unknown object type %i in %s", kind, p->pack_name);
1267         }
1268         unuse_pack(&w_curs);
1269         return retval;
1270 }
1271
1272 int num_packed_objects(const struct packed_git *p)
1273 {
1274         /* See check_packed_git_idx() */
1275         return (p->index_size - 20 - 20 - 4*256) / 24;
1276 }
1277
1278 int nth_packed_object_sha1(const struct packed_git *p, int n,
1279                            unsigned char* sha1)
1280 {
1281         void *index = p->index_base + 256;
1282         if (n < 0 || num_packed_objects(p) <= n)
1283                 return -1;
1284         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1285         return 0;
1286 }
1287
1288 unsigned long find_pack_entry_one(const unsigned char *sha1,
1289                                   struct packed_git *p)
1290 {
1291         unsigned int *level1_ofs = p->index_base;
1292         int hi = ntohl(level1_ofs[*sha1]);
1293         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1294         void *index = p->index_base + 256;
1295
1296         do {
1297                 int mi = (lo + hi) / 2;
1298                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1299                 if (!cmp)
1300                         return ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1301                 if (cmp > 0)
1302                         hi = mi;
1303                 else
1304                         lo = mi+1;
1305         } while (lo < hi);
1306         return 0;
1307 }
1308
1309 static int matches_pack_name(struct packed_git *p, const char *ig)
1310 {
1311         const char *last_c, *c;
1312
1313         if (!strcmp(p->pack_name, ig))
1314                 return 0;
1315
1316         for (c = p->pack_name, last_c = c; *c;)
1317                 if (*c == '/')
1318                         last_c = ++c;
1319                 else
1320                         ++c;
1321         if (!strcmp(last_c, ig))
1322                 return 0;
1323
1324         return 1;
1325 }
1326
1327 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1328 {
1329         struct packed_git *p;
1330         unsigned long offset;
1331
1332         prepare_packed_git();
1333
1334         for (p = packed_git; p; p = p->next) {
1335                 if (ignore_packed) {
1336                         const char **ig;
1337                         for (ig = ignore_packed; *ig; ig++)
1338                                 if (!matches_pack_name(p, *ig))
1339                                         break;
1340                         if (*ig)
1341                                 continue;
1342                 }
1343                 offset = find_pack_entry_one(sha1, p);
1344                 if (offset) {
1345                         e->offset = offset;
1346                         e->p = p;
1347                         hashcpy(e->sha1, sha1);
1348                         return 1;
1349                 }
1350         }
1351         return 0;
1352 }
1353
1354 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1355                                   struct packed_git *packs)
1356 {
1357         struct packed_git *p;
1358
1359         for (p = packs; p; p = p->next) {
1360                 if (find_pack_entry_one(sha1, p))
1361                         return p;
1362         }
1363         return NULL;
1364
1365 }
1366
1367 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1368 {
1369         int status;
1370         unsigned long mapsize, size;
1371         void *map;
1372         z_stream stream;
1373         char hdr[128];
1374
1375         map = map_sha1_file(sha1, &mapsize);
1376         if (!map)
1377                 return error("unable to find %s", sha1_to_hex(sha1));
1378         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1379                 status = error("unable to unpack %s header",
1380                                sha1_to_hex(sha1));
1381         if (parse_sha1_header(hdr, type, &size) < 0)
1382                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1383         else {
1384                 status = 0;
1385                 if (sizep)
1386                         *sizep = size;
1387         }
1388         inflateEnd(&stream);
1389         munmap(map, mapsize);
1390         return status;
1391 }
1392
1393 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1394 {
1395         struct pack_entry e;
1396
1397         if (!find_pack_entry(sha1, &e, NULL)) {
1398                 reprepare_packed_git();
1399                 if (!find_pack_entry(sha1, &e, NULL))
1400                         return sha1_loose_object_info(sha1, type, sizep);
1401         }
1402         return packed_object_info(e.p, e.offset, type, sizep);
1403 }
1404
1405 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1406 {
1407         struct pack_entry e;
1408
1409         if (!find_pack_entry(sha1, &e, NULL)) {
1410                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1411                 return NULL;
1412         }
1413         return unpack_entry(e.p, e.offset, type, size);
1414 }
1415
1416 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1417 {
1418         unsigned long mapsize;
1419         void *map, *buf;
1420         struct pack_entry e;
1421
1422         if (find_pack_entry(sha1, &e, NULL))
1423                 return read_packed_sha1(sha1, type, size);
1424         map = map_sha1_file(sha1, &mapsize);
1425         if (map) {
1426                 buf = unpack_sha1_file(map, mapsize, type, size);
1427                 munmap(map, mapsize);
1428                 return buf;
1429         }
1430         reprepare_packed_git();
1431         if (find_pack_entry(sha1, &e, NULL))
1432                 return read_packed_sha1(sha1, type, size);
1433         return NULL;
1434 }
1435
1436 void *read_object_with_reference(const unsigned char *sha1,
1437                                  const char *required_type,
1438                                  unsigned long *size,
1439                                  unsigned char *actual_sha1_return)
1440 {
1441         char type[20];
1442         void *buffer;
1443         unsigned long isize;
1444         unsigned char actual_sha1[20];
1445
1446         hashcpy(actual_sha1, sha1);
1447         while (1) {
1448                 int ref_length = -1;
1449                 const char *ref_type = NULL;
1450
1451                 buffer = read_sha1_file(actual_sha1, type, &isize);
1452                 if (!buffer)
1453                         return NULL;
1454                 if (!strcmp(type, required_type)) {
1455                         *size = isize;
1456                         if (actual_sha1_return)
1457                                 hashcpy(actual_sha1_return, actual_sha1);
1458                         return buffer;
1459                 }
1460                 /* Handle references */
1461                 else if (!strcmp(type, commit_type))
1462                         ref_type = "tree ";
1463                 else if (!strcmp(type, tag_type))
1464                         ref_type = "object ";
1465                 else {
1466                         free(buffer);
1467                         return NULL;
1468                 }
1469                 ref_length = strlen(ref_type);
1470
1471                 if (memcmp(buffer, ref_type, ref_length) ||
1472                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1473                         free(buffer);
1474                         return NULL;
1475                 }
1476                 free(buffer);
1477                 /* Now we have the ID of the referred-to object in
1478                  * actual_sha1.  Check again. */
1479         }
1480 }
1481
1482 static void write_sha1_file_prepare(void *buf, unsigned long len,
1483                                     const char *type, unsigned char *sha1,
1484                                     unsigned char *hdr, int *hdrlen)
1485 {
1486         SHA_CTX c;
1487
1488         /* Generate the header */
1489         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1490
1491         /* Sha1.. */
1492         SHA1_Init(&c);
1493         SHA1_Update(&c, hdr, *hdrlen);
1494         SHA1_Update(&c, buf, len);
1495         SHA1_Final(sha1, &c);
1496 }
1497
1498 /*
1499  * Link the tempfile to the final place, possibly creating the
1500  * last directory level as you do so.
1501  *
1502  * Returns the errno on failure, 0 on success.
1503  */
1504 static int link_temp_to_file(const char *tmpfile, const char *filename)
1505 {
1506         int ret;
1507         char *dir;
1508
1509         if (!link(tmpfile, filename))
1510                 return 0;
1511
1512         /*
1513          * Try to mkdir the last path component if that failed.
1514          *
1515          * Re-try the "link()" regardless of whether the mkdir
1516          * succeeds, since a race might mean that somebody
1517          * else succeeded.
1518          */
1519         ret = errno;
1520         dir = strrchr(filename, '/');
1521         if (dir) {
1522                 *dir = 0;
1523                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1524                         *dir = '/';
1525                         return -2;
1526                 }
1527                 *dir = '/';
1528                 if (!link(tmpfile, filename))
1529                         return 0;
1530                 ret = errno;
1531         }
1532         return ret;
1533 }
1534
1535 /*
1536  * Move the just written object into its final resting place
1537  */
1538 int move_temp_to_file(const char *tmpfile, const char *filename)
1539 {
1540         int ret = link_temp_to_file(tmpfile, filename);
1541
1542         /*
1543          * Coda hack - coda doesn't like cross-directory links,
1544          * so we fall back to a rename, which will mean that it
1545          * won't be able to check collisions, but that's not a
1546          * big deal.
1547          *
1548          * The same holds for FAT formatted media.
1549          *
1550          * When this succeeds, we just return 0. We have nothing
1551          * left to unlink.
1552          */
1553         if (ret && ret != EEXIST) {
1554                 if (!rename(tmpfile, filename))
1555                         return 0;
1556                 ret = errno;
1557         }
1558         unlink(tmpfile);
1559         if (ret) {
1560                 if (ret != EEXIST) {
1561                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1562                 }
1563                 /* FIXME!!! Collision check here ? */
1564         }
1565
1566         return 0;
1567 }
1568
1569 static int write_buffer(int fd, const void *buf, size_t len)
1570 {
1571         while (len) {
1572                 ssize_t size;
1573
1574                 size = write(fd, buf, len);
1575                 if (!size)
1576                         return error("file write: disk full");
1577                 if (size < 0) {
1578                         if (errno == EINTR || errno == EAGAIN)
1579                                 continue;
1580                         return error("file write error (%s)", strerror(errno));
1581                 }
1582                 len -= size;
1583                 buf = (char *) buf + size;
1584         }
1585         return 0;
1586 }
1587
1588 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1589 {
1590         int hdr_len;
1591         unsigned char c;
1592
1593         c = (type << 4) | (len & 15);
1594         len >>= 4;
1595         hdr_len = 1;
1596         while (len) {
1597                 *hdr++ = c | 0x80;
1598                 hdr_len++;
1599                 c = (len & 0x7f);
1600                 len >>= 7;
1601         }
1602         *hdr = c;
1603         return hdr_len;
1604 }
1605
1606 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1607 {
1608         int obj_type, hdr;
1609
1610         if (use_legacy_headers) {
1611                 while (deflate(stream, 0) == Z_OK)
1612                         /* nothing */;
1613                 return;
1614         }
1615         if (!strcmp(type, blob_type))
1616                 obj_type = OBJ_BLOB;
1617         else if (!strcmp(type, tree_type))
1618                 obj_type = OBJ_TREE;
1619         else if (!strcmp(type, commit_type))
1620                 obj_type = OBJ_COMMIT;
1621         else if (!strcmp(type, tag_type))
1622                 obj_type = OBJ_TAG;
1623         else
1624                 die("trying to generate bogus object of type '%s'", type);
1625         hdr = write_binary_header(stream->next_out, obj_type, len);
1626         stream->total_out = hdr;
1627         stream->next_out += hdr;
1628         stream->avail_out -= hdr;
1629 }
1630
1631 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1632                    unsigned char *sha1)
1633 {
1634         unsigned char hdr[50];
1635         int hdrlen;
1636         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1637         return 0;
1638 }
1639
1640 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1641 {
1642         int size;
1643         unsigned char *compressed;
1644         z_stream stream;
1645         unsigned char sha1[20];
1646         char *filename;
1647         static char tmpfile[PATH_MAX];
1648         unsigned char hdr[50];
1649         int fd, hdrlen;
1650
1651         /* Normally if we have it in the pack then we do not bother writing
1652          * it out into .git/objects/??/?{38} file.
1653          */
1654         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1655         filename = sha1_file_name(sha1);
1656         if (returnsha1)
1657                 hashcpy(returnsha1, sha1);
1658         if (has_sha1_file(sha1))
1659                 return 0;
1660         fd = open(filename, O_RDONLY);
1661         if (fd >= 0) {
1662                 /*
1663                  * FIXME!!! We might do collision checking here, but we'd
1664                  * need to uncompress the old file and check it. Later.
1665                  */
1666                 close(fd);
1667                 return 0;
1668         }
1669
1670         if (errno != ENOENT) {
1671                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1672         }
1673
1674         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1675
1676         fd = mkstemp(tmpfile);
1677         if (fd < 0) {
1678                 if (errno == EPERM)
1679                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1680                 else
1681                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1682         }
1683
1684         /* Set it up */
1685         memset(&stream, 0, sizeof(stream));
1686         deflateInit(&stream, zlib_compression_level);
1687         size = 8 + deflateBound(&stream, len+hdrlen);
1688         compressed = xmalloc(size);
1689
1690         /* Compress it */
1691         stream.next_out = compressed;
1692         stream.avail_out = size;
1693
1694         /* First header.. */
1695         stream.next_in = hdr;
1696         stream.avail_in = hdrlen;
1697         setup_object_header(&stream, type, len);
1698
1699         /* Then the data itself.. */
1700         stream.next_in = buf;
1701         stream.avail_in = len;
1702         while (deflate(&stream, Z_FINISH) == Z_OK)
1703                 /* nothing */;
1704         deflateEnd(&stream);
1705         size = stream.total_out;
1706
1707         if (write_buffer(fd, compressed, size) < 0)
1708                 die("unable to write sha1 file");
1709         fchmod(fd, 0444);
1710         close(fd);
1711         free(compressed);
1712
1713         return move_temp_to_file(tmpfile, filename);
1714 }
1715
1716 /*
1717  * We need to unpack and recompress the object for writing
1718  * it out to a different file.
1719  */
1720 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1721 {
1722         size_t size;
1723         z_stream stream;
1724         unsigned char *unpacked;
1725         unsigned long len;
1726         char type[20];
1727         char hdr[50];
1728         int hdrlen;
1729         void *buf;
1730
1731         /* need to unpack and recompress it by itself */
1732         unpacked = read_packed_sha1(sha1, type, &len);
1733
1734         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1735
1736         /* Set it up */
1737         memset(&stream, 0, sizeof(stream));
1738         deflateInit(&stream, zlib_compression_level);
1739         size = deflateBound(&stream, len + hdrlen);
1740         buf = xmalloc(size);
1741
1742         /* Compress it */
1743         stream.next_out = buf;
1744         stream.avail_out = size;
1745
1746         /* First header.. */
1747         stream.next_in = (void *)hdr;
1748         stream.avail_in = hdrlen;
1749         while (deflate(&stream, 0) == Z_OK)
1750                 /* nothing */;
1751
1752         /* Then the data itself.. */
1753         stream.next_in = unpacked;
1754         stream.avail_in = len;
1755         while (deflate(&stream, Z_FINISH) == Z_OK)
1756                 /* nothing */;
1757         deflateEnd(&stream);
1758         free(unpacked);
1759
1760         *objsize = stream.total_out;
1761         return buf;
1762 }
1763
1764 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1765 {
1766         int retval;
1767         unsigned long objsize;
1768         void *buf = map_sha1_file(sha1, &objsize);
1769
1770         if (buf) {
1771                 retval = write_buffer(fd, buf, objsize);
1772                 munmap(buf, objsize);
1773                 return retval;
1774         }
1775
1776         buf = repack_object(sha1, &objsize);
1777         retval = write_buffer(fd, buf, objsize);
1778         free(buf);
1779         return retval;
1780 }
1781
1782 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1783                        size_t bufsize, size_t *bufposn)
1784 {
1785         char tmpfile[PATH_MAX];
1786         int local;
1787         z_stream stream;
1788         unsigned char real_sha1[20];
1789         unsigned char discard[4096];
1790         int ret;
1791         SHA_CTX c;
1792
1793         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1794
1795         local = mkstemp(tmpfile);
1796         if (local < 0) {
1797                 if (errno == EPERM)
1798                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1799                 else
1800                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1801         }
1802
1803         memset(&stream, 0, sizeof(stream));
1804
1805         inflateInit(&stream);
1806
1807         SHA1_Init(&c);
1808
1809         do {
1810                 ssize_t size;
1811                 if (*bufposn) {
1812                         stream.avail_in = *bufposn;
1813                         stream.next_in = (unsigned char *) buffer;
1814                         do {
1815                                 stream.next_out = discard;
1816                                 stream.avail_out = sizeof(discard);
1817                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1818                                 SHA1_Update(&c, discard, sizeof(discard) -
1819                                             stream.avail_out);
1820                         } while (stream.avail_in && ret == Z_OK);
1821                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1822                                 die("unable to write sha1 file");
1823                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1824                                 stream.avail_in);
1825                         *bufposn = stream.avail_in;
1826                         if (ret != Z_OK)
1827                                 break;
1828                 }
1829                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1830                 if (size <= 0) {
1831                         close(local);
1832                         unlink(tmpfile);
1833                         if (!size)
1834                                 return error("Connection closed?");
1835                         perror("Reading from connection");
1836                         return -1;
1837                 }
1838                 *bufposn += size;
1839         } while (1);
1840         inflateEnd(&stream);
1841
1842         close(local);
1843         SHA1_Final(real_sha1, &c);
1844         if (ret != Z_STREAM_END) {
1845                 unlink(tmpfile);
1846                 return error("File %s corrupted", sha1_to_hex(sha1));
1847         }
1848         if (hashcmp(sha1, real_sha1)) {
1849                 unlink(tmpfile);
1850                 return error("File %s has bad hash", sha1_to_hex(sha1));
1851         }
1852
1853         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1854 }
1855
1856 int has_pack_index(const unsigned char *sha1)
1857 {
1858         struct stat st;
1859         if (stat(sha1_pack_index_name(sha1), &st))
1860                 return 0;
1861         return 1;
1862 }
1863
1864 int has_pack_file(const unsigned char *sha1)
1865 {
1866         struct stat st;
1867         if (stat(sha1_pack_name(sha1), &st))
1868                 return 0;
1869         return 1;
1870 }
1871
1872 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1873 {
1874         struct pack_entry e;
1875         return find_pack_entry(sha1, &e, ignore_packed);
1876 }
1877
1878 int has_sha1_file(const unsigned char *sha1)
1879 {
1880         struct stat st;
1881         struct pack_entry e;
1882
1883         if (find_pack_entry(sha1, &e, NULL))
1884                 return 1;
1885         return find_sha1_file(sha1, &st) ? 1 : 0;
1886 }
1887
1888 /*
1889  * reads from fd as long as possible into a supplied buffer of size bytes.
1890  * If necessary the buffer's size is increased using realloc()
1891  *
1892  * returns 0 if anything went fine and -1 otherwise
1893  *
1894  * NOTE: both buf and size may change, but even when -1 is returned
1895  * you still have to free() it yourself.
1896  */
1897 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1898 {
1899         char* buf = *return_buf;
1900         unsigned long size = *return_size;
1901         int iret;
1902         unsigned long off = 0;
1903
1904         do {
1905                 iret = xread(fd, buf + off, size - off);
1906                 if (iret > 0) {
1907                         off += iret;
1908                         if (off == size) {
1909                                 size *= 2;
1910                                 buf = xrealloc(buf, size);
1911                         }
1912                 }
1913         } while (iret > 0);
1914
1915         *return_buf = buf;
1916         *return_size = off;
1917
1918         if (iret < 0)
1919                 return -1;
1920         return 0;
1921 }
1922
1923 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1924 {
1925         unsigned long size = 4096;
1926         char *buf = xmalloc(size);
1927         int ret;
1928
1929         if (read_pipe(fd, &buf, &size)) {
1930                 free(buf);
1931                 return -1;
1932         }
1933
1934         if (!type)
1935                 type = blob_type;
1936         if (write_object)
1937                 ret = write_sha1_file(buf, size, type, sha1);
1938         else
1939                 ret = hash_sha1_file(buf, size, type, sha1);
1940         free(buf);
1941         return ret;
1942 }
1943
1944 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1945 {
1946         unsigned long size = st->st_size;
1947         void *buf;
1948         int ret;
1949
1950         buf = "";
1951         if (size)
1952                 buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1953         close(fd);
1954         if (buf == MAP_FAILED)
1955                 return -1;
1956
1957         if (!type)
1958                 type = blob_type;
1959         if (write_object)
1960                 ret = write_sha1_file(buf, size, type, sha1);
1961         else
1962                 ret = hash_sha1_file(buf, size, type, sha1);
1963         if (size)
1964                 munmap(buf, size);
1965         return ret;
1966 }
1967
1968 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1969 {
1970         int fd;
1971         char *target;
1972
1973         switch (st->st_mode & S_IFMT) {
1974         case S_IFREG:
1975                 fd = open(path, O_RDONLY);
1976                 if (fd < 0)
1977                         return error("open(\"%s\"): %s", path,
1978                                      strerror(errno));
1979                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1980                         return error("%s: failed to insert into database",
1981                                      path);
1982                 break;
1983         case S_IFLNK:
1984                 target = xmalloc(st->st_size+1);
1985                 if (readlink(path, target, st->st_size+1) != st->st_size) {
1986                         char *errstr = strerror(errno);
1987                         free(target);
1988                         return error("readlink(\"%s\"): %s", path,
1989                                      errstr);
1990                 }
1991                 if (!write_object)
1992                         hash_sha1_file(target, st->st_size, blob_type, sha1);
1993                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1994                         return error("%s: failed to insert into database",
1995                                      path);
1996                 free(target);
1997                 break;
1998         default:
1999                 return error("%s: unsupported file type", path);
2000         }
2001         return 0;
2002 }