git.oblomov.eu Git - git/blob - sha1_file.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  *
   6  * This handles basic git sha1 object files - packing, unpacking,
   7  * creation etc.
   8  */
   9 #include "cache.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "blob.h"
  13 #include "commit.h"
  14 #include "tag.h"
  15 #include "tree.h"
  16
  17 #ifndef O_NOATIME
  18 #if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19 #define O_NOATIME 01000000
  20 #else
  21 #define O_NOATIME 0
  22 #endif
  23 #endif
  24
  25 const unsigned char null_sha1[20];
  26
  27 static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29 signed char hexval_table[256] = {
  30          -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  31          -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  32          -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  33          -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  34          -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  35          -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  36           0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  37           8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  38          -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  39          -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  40          -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  41          -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  42          -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  43          -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  44          -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  45          -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  46          -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  47          -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  48          -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  49          -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  50          -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  51          -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  52          -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  53          -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  54          -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  55          -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  56          -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  57          -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  58          -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  59          -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  60          -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  61          -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  62 };
  63
  64 int get_sha1_hex(const char *hex, unsigned char *sha1)
  65 {
  66         int i;
  67         for (i = 0; i < 20; i++) {
  68                 unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  69                 if (val & ~0xff)
  70                         return -1;
  71                 *sha1++ = val;
  72                 hex += 2;
  73         }
  74         return 0;
  75 }
  76
  77 int safe_create_leading_directories(char *path)
  78 {
  79         char *pos = path;
  80         struct stat st;
  81
  82         if (*pos == '/')
  83                 pos++;
  84
  85         while (pos) {
  86                 pos = strchr(pos, '/');
  87                 if (!pos)
  88                         break;
  89                 *pos = 0;
  90                 if (!stat(path, &st)) {
  91                         /* path exists */
  92                         if (!S_ISDIR(st.st_mode)) {
  93                                 *pos = '/';
  94                                 return -3;
  95                         }
  96                 }
  97                 else if (mkdir(path, 0777)) {
  98                         *pos = '/';
  99                         return -1;
 100                 }
 101                 else if (adjust_shared_perm(path)) {
 102                         *pos = '/';
 103                         return -2;
 104                 }
 105                 *pos++ = '/';
 106         }
 107         return 0;
 108 }
 109
 110 char * sha1_to_hex(const unsigned char *sha1)
 111 {
 112         static int bufno;
 113         static char hexbuffer[4][50];
 114         static const char hex[] = "0123456789abcdef";
 115         char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 116         int i;
 117
 118         for (i = 0; i < 20; i++) {
 119                 unsigned int val = *sha1++;
 120                 *buf++ = hex[val >> 4];
 121                 *buf++ = hex[val & 0xf];
 122         }
 123         *buf = '\0';
 124
 125         return buffer;
 126 }
 127
 128 static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 129 {
 130         int i;
 131         for (i = 0; i < 20; i++) {
 132                 static char hex[] = "0123456789abcdef";
 133                 unsigned int val = sha1[i];
 134                 char *pos = pathbuf + i*2 + (i > 0);
 135                 *pos++ = hex[val >> 4];
 136                 *pos = hex[val & 0xf];
 137         }
 138 }
 139
 140 /*
 141  * NOTE! This returns a statically allocated buffer, so you have to be
 142  * careful about using it. Do a "xstrdup()" if you need to save the
 143  * filename.
 144  *
 145  * Also note that this returns the location for creating.  Reading
 146  * SHA1 file can happen from any alternate directory listed in the
 147  * DB_ENVIRONMENT environment variable if it is not found in
 148  * the primary object database.
 149  */
 150 char *sha1_file_name(const unsigned char *sha1)
 151 {
 152         static char *name, *base;
 153
 154         if (!base) {
 155                 const char *sha1_file_directory = get_object_directory();
 156                 int len = strlen(sha1_file_directory);
 157                 base = xmalloc(len + 60);
 158                 memcpy(base, sha1_file_directory, len);
 159                 memset(base+len, 0, 60);
 160                 base[len] = '/';
 161                 base[len+3] = '/';
 162                 name = base + len + 1;
 163         }
 164         fill_sha1_path(name, sha1);
 165         return base;
 166 }
 167
 168 char *sha1_pack_name(const unsigned char *sha1)
 169 {
 170         static const char hex[] = "0123456789abcdef";
 171         static char *name, *base, *buf;
 172         int i;
 173
 174         if (!base) {
 175                 const char *sha1_file_directory = get_object_directory();
 176                 int len = strlen(sha1_file_directory);
 177                 base = xmalloc(len + 60);
 178                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 179                 name = base + len + 11;
 180         }
 181
 182         buf = name;
 183
 184         for (i = 0; i < 20; i++) {
 185                 unsigned int val = *sha1++;
 186                 *buf++ = hex[val >> 4];
 187                 *buf++ = hex[val & 0xf];
 188         }
 189
 190         return base;
 191 }
 192
 193 char *sha1_pack_index_name(const unsigned char *sha1)
 194 {
 195         static const char hex[] = "0123456789abcdef";
 196         static char *name, *base, *buf;
 197         int i;
 198
 199         if (!base) {
 200                 const char *sha1_file_directory = get_object_directory();
 201                 int len = strlen(sha1_file_directory);
 202                 base = xmalloc(len + 60);
 203                 sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 204                 name = base + len + 11;
 205         }
 206
 207         buf = name;
 208
 209         for (i = 0; i < 20; i++) {
 210                 unsigned int val = *sha1++;
 211                 *buf++ = hex[val >> 4];
 212                 *buf++ = hex[val & 0xf];
 213         }
 214
 215         return base;
 216 }
 217
 218 struct alternate_object_database *alt_odb_list;
 219 static struct alternate_object_database **alt_odb_tail;
 220
 221 static void read_info_alternates(const char * alternates, int depth);
 222
 223 /*
 224  * Prepare alternate object database registry.
 225  *
 226  * The variable alt_odb_list points at the list of struct
 227  * alternate_object_database.  The elements on this list come from
 228  * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 229  * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 230  * whose contents is similar to that environment variable but can be
 231  * LF separated.  Its base points at a statically allocated buffer that
 232  * contains "/the/directory/corresponding/to/.git/objects/...", while
 233  * its name points just after the slash at the end of ".git/objects/"
 234  * in the example above, and has enough space to hold 40-byte hex
 235  * SHA1, an extra slash for the first level indirection, and the
 236  * terminating NUL.
 237  */
 238 static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 239 {
 240         struct stat st;
 241         const char *objdir = get_object_directory();
 242         struct alternate_object_database *ent;
 243         struct alternate_object_database *alt;
 244         /* 43 = 40-byte + 2 '/' + terminating NUL */
 245         int pfxlen = len;
 246         int entlen = pfxlen + 43;
 247         int base_len = -1;
 248
 249         if (*entry != '/' && relative_base) {
 250                 /* Relative alt-odb */
 251                 if (base_len < 0)
 252                         base_len = strlen(relative_base) + 1;
 253                 entlen += base_len;
 254                 pfxlen += base_len;
 255         }
 256         ent = xmalloc(sizeof(*ent) + entlen);
 257
 258         if (*entry != '/' && relative_base) {
 259                 memcpy(ent->base, relative_base, base_len - 1);
 260                 ent->base[base_len - 1] = '/';
 261                 memcpy(ent->base + base_len, entry, len);
 262         }
 263         else
 264                 memcpy(ent->base, entry, pfxlen);
 265
 266         ent->name = ent->base + pfxlen + 1;
 267         ent->base[pfxlen + 3] = '/';
 268         ent->base[pfxlen] = ent->base[entlen-1] = 0;
 269
 270         /* Detect cases where alternate disappeared */
 271         if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 272                 error("object directory %s does not exist; "
 273                       "check .git/objects/info/alternates.",
 274                       ent->base);
 275                 free(ent);
 276                 return -1;
 277         }
 278
 279         /* Prevent the common mistake of listing the same
 280          * thing twice, or object directory itself.
 281          */
 282         for (alt = alt_odb_list; alt; alt = alt->next) {
 283                 if (!memcmp(ent->base, alt->base, pfxlen)) {
 284                         free(ent);
 285                         return -1;
 286                 }
 287         }
 288         if (!memcmp(ent->base, objdir, pfxlen)) {
 289                 free(ent);
 290                 return -1;
 291         }
 292
 293         /* add the alternate entry */
 294         *alt_odb_tail = ent;
 295         alt_odb_tail = &(ent->next);
 296         ent->next = NULL;
 297
 298         /* recursively add alternates */
 299         read_info_alternates(ent->base, depth + 1);
 300
 301         ent->base[pfxlen] = '/';
 302
 303         return 0;
 304 }
 305
 306 static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 307                                  const char *relative_base, int depth)
 308 {
 309         const char *cp, *last;
 310
 311         if (depth > 5) {
 312                 error("%s: ignoring alternate object stores, nesting too deep.",
 313                                 relative_base);
 314                 return;
 315         }
 316
 317         last = alt;
 318         while (last < ep) {
 319                 cp = last;
 320                 if (cp < ep && *cp == '#') {
 321                         while (cp < ep && *cp != sep)
 322                                 cp++;
 323                         last = cp + 1;
 324                         continue;
 325                 }
 326                 while (cp < ep && *cp != sep)
 327                         cp++;
 328                 if (last != cp) {
 329                         if ((*last != '/') && depth) {
 330                                 error("%s: ignoring relative alternate object store %s",
 331                                                 relative_base, last);
 332                         } else {
 333                                 link_alt_odb_entry(last, cp - last,
 334                                                 relative_base, depth);
 335                         }
 336                 }
 337                 while (cp < ep && *cp == sep)
 338                         cp++;
 339                 last = cp;
 340         }
 341 }
 342
 343 static void read_info_alternates(const char * relative_base, int depth)
 344 {
 345         char *map;
 346         struct stat st;
 347         char path[PATH_MAX];
 348         int fd;
 349
 350         sprintf(path, "%s/info/alternates", relative_base);
 351         fd = open(path, O_RDONLY);
 352         if (fd < 0)
 353                 return;
 354         if (fstat(fd, &st) || (st.st_size == 0)) {
 355                 close(fd);
 356                 return;
 357         }
 358         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 359         close(fd);
 360
 361         link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 362
 363         munmap(map, st.st_size);
 364 }
 365
 366 void prepare_alt_odb(void)
 367 {
 368         const char *alt;
 369
 370         alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 371         if (!alt) alt = "";
 372
 373         if (alt_odb_tail)
 374                 return;
 375         alt_odb_tail = &alt_odb_list;
 376         link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 377
 378         read_info_alternates(get_object_directory(), 0);
 379 }
 380
 381 static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 382 {
 383         char *name = sha1_file_name(sha1);
 384         struct alternate_object_database *alt;
 385
 386         if (!stat(name, st))
 387                 return name;
 388         prepare_alt_odb();
 389         for (alt = alt_odb_list; alt; alt = alt->next) {
 390                 name = alt->name;
 391                 fill_sha1_path(name, sha1);
 392                 if (!stat(alt->base, st))
 393                         return alt->base;
 394         }
 395         return NULL;
 396 }
 397
 398 static unsigned int pack_used_ctr;
 399 static unsigned int pack_mmap_calls;
 400 static unsigned int peak_pack_open_windows;
 401 static unsigned int pack_open_windows;
 402 static size_t peak_pack_mapped;
 403 static size_t pack_mapped;
 404 static size_t page_size;
 405 struct packed_git *packed_git;
 406
 407 void pack_report()
 408 {
 409         fprintf(stderr,
 410                 "pack_report: getpagesize()            = %10lu\n"
 411                 "pack_report: core.packedGitWindowSize = %10lu\n"
 412                 "pack_report: core.packedGitLimit      = %10lu\n",
 413                 page_size,
 414                 packed_git_window_size,
 415                 packed_git_limit);
 416         fprintf(stderr,
 417                 "pack_report: pack_used_ctr            = %10u\n"
 418                 "pack_report: pack_mmap_calls          = %10u\n"
 419                 "pack_report: pack_open_windows        = %10u / %10u\n"
 420                 "pack_report: pack_mapped              = %10lu / %10lu\n",
 421                 pack_used_ctr,
 422                 pack_mmap_calls,
 423                 pack_open_windows, peak_pack_open_windows,
 424                 pack_mapped, peak_pack_mapped);
 425 }
 426
 427 static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 428                                 void **idx_map_)
 429 {
 430         void *idx_map;
 431         unsigned int *index;
 432         unsigned long idx_size;
 433         int nr, i;
 434         int fd = open(path, O_RDONLY);
 435         struct stat st;
 436         if (fd < 0)
 437                 return -1;
 438         if (fstat(fd, &st)) {
 439                 close(fd);
 440                 return -1;
 441         }
 442         idx_size = st.st_size;
 443         idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 444         close(fd);
 445
 446         index = idx_map;
 447         *idx_map_ = idx_map;
 448         *idx_size_ = idx_size;
 449
 450         /* check index map */
 451         if (idx_size < 4*256 + 20 + 20)
 452                 return error("index file too small");
 453         nr = 0;
 454         for (i = 0; i < 256; i++) {
 455                 unsigned int n = ntohl(index[i]);
 456                 if (n < nr)
 457                         return error("non-monotonic index");
 458                 nr = n;
 459         }
 460
 461         /*
 462          * Total size:
 463          *  - 256 index entries 4 bytes each
 464          *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 465          *  - 20-byte SHA1 of the packfile
 466          *  - 20-byte SHA1 file checksum
 467          */
 468         if (idx_size != 4*256 + nr * 24 + 20 + 20)
 469                 return error("wrong index file size");
 470
 471         return 0;
 472 }
 473
 474 static void scan_windows(struct packed_git *p,
 475         struct packed_git **lru_p,
 476         struct pack_window **lru_w,
 477         struct pack_window **lru_l)
 478 {
 479         struct pack_window *w, *w_l;
 480
 481         for (w_l = NULL, w = p->windows; w; w = w->next) {
 482                 if (!w->inuse_cnt) {
 483                         if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 484                                 *lru_p = p;
 485                                 *lru_w = w;
 486                                 *lru_l = w_l;
 487                         }
 488                 }
 489                 w_l = w;
 490         }
 491 }
 492
 493 static int unuse_one_window(struct packed_git *current)
 494 {
 495         struct packed_git *p, *lru_p = NULL;
 496         struct pack_window *lru_w = NULL, *lru_l = NULL;
 497
 498         if (current)
 499                 scan_windows(current, &lru_p, &lru_w, &lru_l);
 500         for (p = packed_git; p; p = p->next)
 501                 scan_windows(p, &lru_p, &lru_w, &lru_l);
 502         if (lru_p) {
 503                 munmap(lru_w->base, lru_w->len);
 504                 pack_mapped -= lru_w->len;
 505                 if (lru_l)
 506                         lru_l->next = lru_w->next;
 507                 else {
 508                         lru_p->windows = lru_w->next;
 509                         if (!lru_p->windows && lru_p != current) {
 510                                 close(lru_p->pack_fd);
 511                                 lru_p->pack_fd = -1;
 512                         }
 513                 }
 514                 free(lru_w);
 515                 pack_open_windows--;
 516                 return 1;
 517         }
 518         return 0;
 519 }
 520
 521 void release_pack_memory(size_t need)
 522 {
 523         size_t cur = pack_mapped;
 524         while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 525                 ; /* nothing */
 526 }
 527
 528 void unuse_pack(struct pack_window **w_cursor)
 529 {
 530         struct pack_window *w = *w_cursor;
 531         if (w) {
 532                 w->inuse_cnt--;
 533                 *w_cursor = NULL;
 534         }
 535 }
 536
 537 static void open_packed_git(struct packed_git *p)
 538 {
 539         struct stat st;
 540         struct pack_header hdr;
 541         unsigned char sha1[20];
 542         unsigned char *idx_sha1;
 543
 544         p->pack_fd = open(p->pack_name, O_RDONLY);
 545         if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 546                 die("packfile %s cannot be opened", p->pack_name);
 547
 548         /* If we created the struct before we had the pack we lack size. */
 549         if (!p->pack_size) {
 550                 if (!S_ISREG(st.st_mode))
 551                         die("packfile %s not a regular file", p->pack_name);
 552                 p->pack_size = st.st_size;
 553         } else if (p->pack_size != st.st_size)
 554                 die("packfile %s size changed", p->pack_name);
 555
 556         /* Verify we recognize this pack file format. */
 557         read_or_die(p->pack_fd, &hdr, sizeof(hdr));
 558         if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 559                 die("file %s is not a GIT packfile", p->pack_name);
 560         if (!pack_version_ok(hdr.hdr_version))
 561                 die("packfile %s is version %u and not supported"
 562                         " (try upgrading GIT to a newer version)",
 563                         p->pack_name, ntohl(hdr.hdr_version));
 564
 565         /* Verify the pack matches its index. */
 566         if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 567                 die("packfile %s claims to have %u objects"
 568                         " while index size indicates %u objects",
 569                         p->pack_name, ntohl(hdr.hdr_entries),
 570                         num_packed_objects(p));
 571         if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 572                 die("end of packfile %s is unavailable", p->pack_name);
 573         read_or_die(p->pack_fd, sha1, sizeof(sha1));
 574         idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 575         if (hashcmp(sha1, idx_sha1))
 576                 die("packfile %s does not match index", p->pack_name);
 577 }
 578
 579 static int in_window(struct pack_window *win, unsigned long offset)
 580 {
 581         /* We must promise at least 20 bytes (one hash) after the
 582          * offset is available from this window, otherwise the offset
 583          * is not actually in this window and a different window (which
 584          * has that one hash excess) must be used.  This is to support
 585          * the object header and delta base parsing routines below.
 586          */
 587         off_t win_off = win->offset;
 588         return win_off <= offset
 589                 && (offset + 20) <= (win_off + win->len);
 590 }
 591
 592 unsigned char* use_pack(struct packed_git *p,
 593                 struct pack_window **w_cursor,
 594                 unsigned long offset,
 595                 unsigned int *left)
 596 {
 597         struct pack_window *win = *w_cursor;
 598
 599         if (p->pack_fd == -1)
 600                 open_packed_git(p);
 601
 602         /* Since packfiles end in a hash of their content and its
 603          * pointless to ask for an offset into the middle of that
 604          * hash, and the in_window function above wouldn't match
 605          * don't allow an offset too close to the end of the file.
 606          */
 607         if (offset > (p->pack_size - 20))
 608                 die("offset beyond end of packfile (truncated pack?)");
 609
 610         if (!win || !in_window(win, offset)) {
 611                 if (win)
 612                         win->inuse_cnt--;
 613                 for (win = p->windows; win; win = win->next) {
 614                         if (in_window(win, offset))
 615                                 break;
 616                 }
 617                 if (!win) {
 618                         if (!page_size)
 619                                 page_size = getpagesize();
 620                         win = xcalloc(1, sizeof(*win));
 621                         win->offset = (offset / page_size) * page_size;
 622                         win->len = p->pack_size - win->offset;
 623                         if (win->len > packed_git_window_size)
 624                                 win->len = packed_git_window_size;
 625                         pack_mapped += win->len;
 626                         while (packed_git_limit < pack_mapped
 627                                 && unuse_one_window(p))
 628                                 ; /* nothing */
 629                         win->base = xmmap(NULL, win->len,
 630                                 PROT_READ, MAP_PRIVATE,
 631                                 p->pack_fd, win->offset);
 632                         if (win->base == MAP_FAILED)
 633                                 die("packfile %s cannot be mapped: %s",
 634                                         p->pack_name,
 635                                         strerror(errno));
 636                         pack_mmap_calls++;
 637                         pack_open_windows++;
 638                         if (pack_mapped > peak_pack_mapped)
 639                                 peak_pack_mapped = pack_mapped;
 640                         if (pack_open_windows > peak_pack_open_windows)
 641                                 peak_pack_open_windows = pack_open_windows;
 642                         win->next = p->windows;
 643                         p->windows = win;
 644                 }
 645         }
 646         if (win != *w_cursor) {
 647                 win->last_used = pack_used_ctr++;
 648                 win->inuse_cnt++;
 649                 *w_cursor = win;
 650         }
 651         offset -= win->offset;
 652         if (left)
 653                 *left = win->len - offset;
 654         return win->base + offset;
 655 }
 656
 657 struct packed_git *add_packed_git(char *path, int path_len, int local)
 658 {
 659         struct stat st;
 660         struct packed_git *p;
 661         unsigned long idx_size;
 662         void *idx_map;
 663         unsigned char sha1[20];
 664
 665         if (check_packed_git_idx(path, &idx_size, &idx_map))
 666                 return NULL;
 667
 668         /* do we have a corresponding .pack file? */
 669         strcpy(path + path_len - 4, ".pack");
 670         if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 671                 munmap(idx_map, idx_size);
 672                 return NULL;
 673         }
 674         /* ok, it looks sane as far as we can check without
 675          * actually mapping the pack file.
 676          */
 677         p = xmalloc(sizeof(*p) + path_len + 2);
 678         strcpy(p->pack_name, path);
 679         p->index_size = idx_size;
 680         p->pack_size = st.st_size;
 681         p->index_base = idx_map;
 682         p->next = NULL;
 683         p->windows = NULL;
 684         p->pack_fd = -1;
 685         p->pack_local = local;
 686         if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 687                 hashcpy(p->sha1, sha1);
 688         return p;
 689 }
 690
 691 struct packed_git *parse_pack_index(unsigned char *sha1)
 692 {
 693         char *path = sha1_pack_index_name(sha1);
 694         return parse_pack_index_file(sha1, path);
 695 }
 696
 697 struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 698 {
 699         struct packed_git *p;
 700         unsigned long idx_size;
 701         void *idx_map;
 702         char *path;
 703
 704         if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 705                 return NULL;
 706
 707         path = sha1_pack_name(sha1);
 708
 709         p = xmalloc(sizeof(*p) + strlen(path) + 2);
 710         strcpy(p->pack_name, path);
 711         p->index_size = idx_size;
 712         p->pack_size = 0;
 713         p->index_base = idx_map;
 714         p->next = NULL;
 715         p->windows = NULL;
 716         p->pack_fd = -1;
 717         hashcpy(p->sha1, sha1);
 718         return p;
 719 }
 720
 721 void install_packed_git(struct packed_git *pack)
 722 {
 723         pack->next = packed_git;
 724         packed_git = pack;
 725 }
 726
 727 static void prepare_packed_git_one(char *objdir, int local)
 728 {
 729         char path[PATH_MAX];
 730         int len;
 731         DIR *dir;
 732         struct dirent *de;
 733
 734         sprintf(path, "%s/pack", objdir);
 735         len = strlen(path);
 736         dir = opendir(path);
 737         if (!dir) {
 738                 if (errno != ENOENT)
 739                         error("unable to open object pack directory: %s: %s",
 740                               path, strerror(errno));
 741                 return;
 742         }
 743         path[len++] = '/';
 744         while ((de = readdir(dir)) != NULL) {
 745                 int namelen = strlen(de->d_name);
 746                 struct packed_git *p;
 747
 748                 if (!has_extension(de->d_name, ".idx"))
 749                         continue;
 750
 751                 /* we have .idx.  Is it a file we can map? */
 752                 strcpy(path + len, de->d_name);
 753                 for (p = packed_git; p; p = p->next) {
 754                         if (!memcmp(path, p->pack_name, len + namelen - 4))
 755                                 break;
 756                 }
 757                 if (p)
 758                         continue;
 759                 p = add_packed_git(path, len + namelen, local);
 760                 if (!p)
 761                         continue;
 762                 p->next = packed_git;
 763                 packed_git = p;
 764         }
 765         closedir(dir);
 766 }
 767
 768 static int prepare_packed_git_run_once = 0;
 769 void prepare_packed_git(void)
 770 {
 771         struct alternate_object_database *alt;
 772
 773         if (prepare_packed_git_run_once)
 774                 return;
 775         prepare_packed_git_one(get_object_directory(), 1);
 776         prepare_alt_odb();
 777         for (alt = alt_odb_list; alt; alt = alt->next) {
 778                 alt->name[-1] = 0;
 779                 prepare_packed_git_one(alt->base, 0);
 780                 alt->name[-1] = '/';
 781         }
 782         prepare_packed_git_run_once = 1;
 783 }
 784
 785 void reprepare_packed_git(void)
 786 {
 787         prepare_packed_git_run_once = 0;
 788         prepare_packed_git();
 789 }
 790
 791 int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 792 {
 793         unsigned char real_sha1[20];
 794         hash_sha1_file(map, size, type, real_sha1);
 795         return hashcmp(sha1, real_sha1) ? -1 : 0;
 796 }
 797
 798 void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 799 {
 800         struct stat st;
 801         void *map;
 802         int fd;
 803         char *filename = find_sha1_file(sha1, &st);
 804
 805         if (!filename) {
 806                 return NULL;
 807         }
 808
 809         fd = open(filename, O_RDONLY | sha1_file_open_flag);
 810         if (fd < 0) {
 811                 /* See if it works without O_NOATIME */
 812                 switch (sha1_file_open_flag) {
 813                 default:
 814                         fd = open(filename, O_RDONLY);
 815                         if (fd >= 0)
 816                                 break;
 817                 /* Fallthrough */
 818                 case 0:
 819                         return NULL;
 820                 }
 821
 822                 /* If it failed once, it will probably fail again.
 823                  * Stop using O_NOATIME
 824                  */
 825                 sha1_file_open_flag = 0;
 826         }
 827         map = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 828         close(fd);
 829         *size = st.st_size;
 830         return map;
 831 }
 832
 833 int legacy_loose_object(unsigned char *map)
 834 {
 835         unsigned int word;
 836
 837         /*
 838          * Is it a zlib-compressed buffer? If so, the first byte
 839          * must be 0x78 (15-bit window size, deflated), and the
 840          * first 16-bit word is evenly divisible by 31
 841          */
 842         word = (map[0] << 8) + map[1];
 843         if (map[0] == 0x78 && !(word % 31))
 844                 return 1;
 845         else
 846                 return 0;
 847 }
 848
 849 unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 850 {
 851         unsigned shift;
 852         unsigned char c;
 853         unsigned long size;
 854         unsigned long used = 0;
 855
 856         c = buf[used++];
 857         *type = (c >> 4) & 7;
 858         size = c & 15;
 859         shift = 4;
 860         while (c & 0x80) {
 861                 if (len <= used)
 862                         return 0;
 863                 if (sizeof(long) * 8 <= shift)
 864                         return 0;
 865                 c = buf[used++];
 866                 size += (c & 0x7f) << shift;
 867                 shift += 7;
 868         }
 869         *sizep = size;
 870         return used;
 871 }
 872
 873 static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 874 {
 875         unsigned long size, used;
 876         static const char valid_loose_object_type[8] = {
 877                 0, /* OBJ_EXT */
 878                 1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 879                 0, /* "delta" and others are invalid in a loose object */
 880         };
 881         enum object_type type;
 882
 883         /* Get the data stream */
 884         memset(stream, 0, sizeof(*stream));
 885         stream->next_in = map;
 886         stream->avail_in = mapsize;
 887         stream->next_out = buffer;
 888         stream->avail_out = bufsiz;
 889
 890         if (legacy_loose_object(map)) {
 891                 inflateInit(stream);
 892                 return inflate(stream, 0);
 893         }
 894
 895         used = unpack_object_header_gently(map, mapsize, &type, &size);
 896         if (!used || !valid_loose_object_type[type])
 897                 return -1;
 898         map += used;
 899         mapsize -= used;
 900
 901         /* Set up the stream for the rest.. */
 902         stream->next_in = map;
 903         stream->avail_in = mapsize;
 904         inflateInit(stream);
 905
 906         /* And generate the fake traditional header */
 907         stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 908                                          type_names[type], size);
 909         return 0;
 910 }
 911
 912 static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 913 {
 914         int bytes = strlen(buffer) + 1;
 915         unsigned char *buf = xmalloc(1+size);
 916         unsigned long n;
 917
 918         n = stream->total_out - bytes;
 919         if (n > size)
 920                 n = size;
 921         memcpy(buf, (char *) buffer + bytes, n);
 922         bytes = n;
 923         if (bytes < size) {
 924                 stream->next_out = buf + bytes;
 925                 stream->avail_out = size - bytes;
 926                 while (inflate(stream, Z_FINISH) == Z_OK)
 927                         /* nothing */;
 928         }
 929         buf[size] = 0;
 930         inflateEnd(stream);
 931         return buf;
 932 }
 933
 934 /*
 935  * We used to just use "sscanf()", but that's actually way
 936  * too permissive for what we want to check. So do an anal
 937  * object header parse by hand.
 938  */
 939 static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 940 {
 941         int i;
 942         unsigned long size;
 943
 944         /*
 945          * The type can be at most ten bytes (including the
 946          * terminating '\0' that we add), and is followed by
 947          * a space.
 948          */
 949         i = 10;
 950         for (;;) {
 951                 char c = *hdr++;
 952                 if (c == ' ')
 953                         break;
 954                 if (!--i)
 955                         return -1;
 956                 *type++ = c;
 957         }
 958         *type = 0;
 959
 960         /*
 961          * The length must follow immediately, and be in canonical
 962          * decimal format (ie "010" is not valid).
 963          */
 964         size = *hdr++ - '0';
 965         if (size > 9)
 966                 return -1;
 967         if (size) {
 968                 for (;;) {
 969                         unsigned long c = *hdr - '0';
 970                         if (c > 9)
 971                                 break;
 972                         hdr++;
 973                         size = size * 10 + c;
 974                 }
 975         }
 976         *sizep = size;
 977
 978         /*
 979          * The length must be followed by a zero byte
 980          */
 981         return *hdr ? -1 : 0;
 982 }
 983
 984 void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 985 {
 986         int ret;
 987         z_stream stream;
 988         char hdr[8192];
 989
 990         ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 991         if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 992                 return NULL;
 993
 994         return unpack_sha1_rest(&stream, hdr, *size);
 995 }
 996
 997 static unsigned long get_delta_base(struct packed_git *p,
 998                                     struct pack_window **w_curs,
 999                                     unsigned long offset,
1000                                     enum object_type kind,
1001                                     unsigned long delta_obj_offset,
1002                                     unsigned long *base_obj_offset)
1003 {
1004         unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
1005         unsigned long base_offset;
1006
1007         /* use_pack() assured us we have [base_info, base_info + 20)
1008          * as a range that we can look at without walking off the
1009          * end of the mapped window.  Its actually the hash size
1010          * that is assured.  An OFS_DELTA longer than the hash size
1011          * is stupid, as then a REF_DELTA would be smaller to store.
1012          */
1013         if (kind == OBJ_OFS_DELTA) {
1014                 unsigned used = 0;
1015                 unsigned char c = base_info[used++];
1016                 base_offset = c & 127;
1017                 while (c & 128) {
1018                         base_offset += 1;
1019                         if (!base_offset || base_offset & ~(~0UL >> 7))
1020                                 die("offset value overflow for delta base object");
1021                         c = base_info[used++];
1022                         base_offset = (base_offset << 7) + (c & 127);
1023                 }
1024                 base_offset = delta_obj_offset - base_offset;
1025                 if (base_offset >= delta_obj_offset)
1026                         die("delta base offset out of bound");
1027                 offset += used;
1028         } else if (kind == OBJ_REF_DELTA) {
1029                 /* The base entry _must_ be in the same pack */
1030                 base_offset = find_pack_entry_one(base_info, p);
1031                 if (!base_offset)
1032                         die("failed to find delta-pack base object %s",
1033                                 sha1_to_hex(base_info));
1034                 offset += 20;
1035         } else
1036                 die("I am totally screwed");
1037         *base_obj_offset = base_offset;
1038         return offset;
1039 }
1040
1041 /* forward declaration for a mutually recursive function */
1042 static int packed_object_info(struct packed_git *p, unsigned long offset,
1043                               char *type, unsigned long *sizep);
1044
1045 static int packed_delta_info(struct packed_git *p,
1046                              struct pack_window **w_curs,
1047                              unsigned long offset,
1048                              enum object_type kind,
1049                              unsigned long obj_offset,
1050                              char *type,
1051                              unsigned long *sizep)
1052 {
1053         unsigned long base_offset;
1054
1055         offset = get_delta_base(p, w_curs, offset, kind,
1056                 obj_offset, &base_offset);
1057
1058         /* We choose to only get the type of the base object and
1059          * ignore potentially corrupt pack file that expects the delta
1060          * based on a base with a wrong size.  This saves tons of
1061          * inflate() calls.
1062          */
1063         if (packed_object_info(p, base_offset, type, NULL))
1064                 die("cannot get info for delta-pack base");
1065
1066         if (sizep) {
1067                 const unsigned char *data;
1068                 unsigned char delta_head[20], *in;
1069                 unsigned long result_size;
1070                 z_stream stream;
1071                 int st;
1072
1073                 memset(&stream, 0, sizeof(stream));
1074                 stream.next_out = delta_head;
1075                 stream.avail_out = sizeof(delta_head);
1076
1077                 inflateInit(&stream);
1078                 do {
1079                         in = use_pack(p, w_curs, offset, &stream.avail_in);
1080                         stream.next_in = in;
1081                         st = inflate(&stream, Z_FINISH);
1082                         offset += stream.next_in - in;
1083                 } while ((st == Z_OK || st == Z_BUF_ERROR)
1084                         && stream.total_out < sizeof(delta_head));
1085                 inflateEnd(&stream);
1086                 if ((st != Z_STREAM_END) &&
1087                     stream.total_out != sizeof(delta_head))
1088                         die("delta data unpack-initial failed");
1089
1090                 /* Examine the initial part of the delta to figure out
1091                  * the result size.
1092                  */
1093                 data = delta_head;
1094
1095                 /* ignore base size */
1096                 get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1097
1098                 /* Read the result size */
1099                 result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1100                 *sizep = result_size;
1101         }
1102         return 0;
1103 }
1104
1105 static unsigned long unpack_object_header(struct packed_git *p,
1106                 struct pack_window **w_curs,
1107                 unsigned long offset,
1108                 enum object_type *type,
1109                 unsigned long *sizep)
1110 {
1111         unsigned char *base;
1112         unsigned int left;
1113         unsigned long used;
1114
1115         /* use_pack() assures us we have [base, base + 20) available
1116          * as a range that we can look at at.  (Its actually the hash
1117          * size that is assurred.)  With our object header encoding
1118          * the maximum deflated object size is 2^137, which is just
1119          * insane, so we know won't exceed what we have been given.
1120          */
1121         base = use_pack(p, w_curs, offset, &left);
1122         used = unpack_object_header_gently(base, left, type, sizep);
1123         if (!used)
1124                 die("object offset outside of pack file");
1125
1126         return offset + used;
1127 }
1128
1129 void packed_object_info_detail(struct packed_git *p,
1130                                unsigned long offset,
1131                                char *type,
1132                                unsigned long *size,
1133                                unsigned long *store_size,
1134                                unsigned int *delta_chain_length,
1135                                unsigned char *base_sha1)
1136 {
1137         struct pack_window *w_curs = NULL;
1138         unsigned long obj_offset, val;
1139         unsigned char *next_sha1;
1140         enum object_type kind;
1141
1142         *delta_chain_length = 0;
1143         obj_offset = offset;
1144         offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1145
1146         for (;;) {
1147                 switch (kind) {
1148                 default:
1149                         die("pack %s contains unknown object type %d",
1150                             p->pack_name, kind);
1151                 case OBJ_COMMIT:
1152                 case OBJ_TREE:
1153                 case OBJ_BLOB:
1154                 case OBJ_TAG:
1155                         strcpy(type, type_names[kind]);
1156                         *store_size = 0; /* notyet */
1157                         unuse_pack(&w_curs);
1158                         return;
1159                 case OBJ_OFS_DELTA:
1160                         get_delta_base(p, &w_curs, offset, kind,
1161                                 obj_offset, &offset);
1162                         if (*delta_chain_length == 0) {
1163                                 /* TODO: find base_sha1 as pointed by offset */
1164                         }
1165                         break;
1166                 case OBJ_REF_DELTA:
1167                         next_sha1 = use_pack(p, &w_curs, offset, NULL);
1168                         if (*delta_chain_length == 0)
1169                                 hashcpy(base_sha1, next_sha1);
1170                         offset = find_pack_entry_one(next_sha1, p);
1171                         break;
1172                 }
1173                 obj_offset = offset;
1174                 offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1175                 (*delta_chain_length)++;
1176         }
1177 }
1178
1179 static int packed_object_info(struct packed_git *p, unsigned long offset,
1180                               char *type, unsigned long *sizep)
1181 {
1182         struct pack_window *w_curs = NULL;
1183         unsigned long size, obj_offset = offset;
1184         enum object_type kind;
1185         int r;
1186
1187         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1188
1189         switch (kind) {
1190         case OBJ_OFS_DELTA:
1191         case OBJ_REF_DELTA:
1192                 r = packed_delta_info(p, &w_curs, offset, kind,
1193                         obj_offset, type, sizep);
1194                 unuse_pack(&w_curs);
1195                 return r;
1196         case OBJ_COMMIT:
1197         case OBJ_TREE:
1198         case OBJ_BLOB:
1199         case OBJ_TAG:
1200                 strcpy(type, type_names[kind]);
1201                 unuse_pack(&w_curs);
1202                 break;
1203         default:
1204                 die("pack %s contains unknown object type %d",
1205                     p->pack_name, kind);
1206         }
1207         if (sizep)
1208                 *sizep = size;
1209         return 0;
1210 }
1211
1212 static void *unpack_compressed_entry(struct packed_git *p,
1213                                     struct pack_window **w_curs,
1214                                     unsigned long offset,
1215                                     unsigned long size)
1216 {
1217         int st;
1218         z_stream stream;
1219         unsigned char *buffer, *in;
1220
1221         buffer = xmalloc(size + 1);
1222         buffer[size] = 0;
1223         memset(&stream, 0, sizeof(stream));
1224         stream.next_out = buffer;
1225         stream.avail_out = size;
1226
1227         inflateInit(&stream);
1228         do {
1229                 in = use_pack(p, w_curs, offset, &stream.avail_in);
1230                 stream.next_in = in;
1231                 st = inflate(&stream, Z_FINISH);
1232                 offset += stream.next_in - in;
1233         } while (st == Z_OK || st == Z_BUF_ERROR);
1234         inflateEnd(&stream);
1235         if ((st != Z_STREAM_END) || stream.total_out != size) {
1236                 free(buffer);
1237                 return NULL;
1238         }
1239
1240         return buffer;
1241 }
1242
1243 static void *unpack_delta_entry(struct packed_git *p,
1244                                 struct pack_window **w_curs,
1245                                 unsigned long offset,
1246                                 unsigned long delta_size,
1247                                 enum object_type kind,
1248                                 unsigned long obj_offset,
1249                                 char *type,
1250                                 unsigned long *sizep)
1251 {
1252         void *delta_data, *result, *base;
1253         unsigned long result_size, base_size, base_offset;
1254
1255         offset = get_delta_base(p, w_curs, offset, kind,
1256                 obj_offset, &base_offset);
1257         base = unpack_entry(p, base_offset, type, &base_size);
1258         if (!base)
1259                 die("failed to read delta base object at %lu from %s",
1260                     base_offset, p->pack_name);
1261
1262         delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1263         result = patch_delta(base, base_size,
1264                              delta_data, delta_size,
1265                              &result_size);
1266         if (!result)
1267                 die("failed to apply delta");
1268         free(delta_data);
1269         free(base);
1270         *sizep = result_size;
1271         return result;
1272 }
1273
1274 void *unpack_entry(struct packed_git *p, unsigned long offset,
1275                           char *type, unsigned long *sizep)
1276 {
1277         struct pack_window *w_curs = NULL;
1278         unsigned long size, obj_offset = offset;
1279         enum object_type kind;
1280         void *retval;
1281
1282         offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1283         switch (kind) {
1284         case OBJ_OFS_DELTA:
1285         case OBJ_REF_DELTA:
1286                 retval = unpack_delta_entry(p, &w_curs, offset, size,
1287                         kind, obj_offset, type, sizep);
1288                 break;
1289         case OBJ_COMMIT:
1290         case OBJ_TREE:
1291         case OBJ_BLOB:
1292         case OBJ_TAG:
1293                 strcpy(type, type_names[kind]);
1294                 *sizep = size;
1295                 retval = unpack_compressed_entry(p, &w_curs, offset, size);
1296                 break;
1297         default:
1298                 die("unknown object type %i in %s", kind, p->pack_name);
1299         }
1300         unuse_pack(&w_curs);
1301         return retval;
1302 }
1303
1304 int num_packed_objects(const struct packed_git *p)
1305 {
1306         /* See check_packed_git_idx() */
1307         return (p->index_size - 20 - 20 - 4*256) / 24;
1308 }
1309
1310 int nth_packed_object_sha1(const struct packed_git *p, int n,
1311                            unsigned char* sha1)
1312 {
1313         void *index = p->index_base + 256;
1314         if (n < 0 || num_packed_objects(p) <= n)
1315                 return -1;
1316         hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1317         return 0;
1318 }
1319
1320 unsigned long find_pack_entry_one(const unsigned char *sha1,
1321                                   struct packed_git *p)
1322 {
1323         unsigned int *level1_ofs = p->index_base;
1324         int hi = ntohl(level1_ofs[*sha1]);
1325         int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1326         void *index = p->index_base + 256;
1327
1328         do {
1329                 int mi = (lo + hi) / 2;
1330                 int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1331                 if (!cmp)
1332                         return ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1333                 if (cmp > 0)
1334                         hi = mi;
1335                 else
1336                         lo = mi+1;
1337         } while (lo < hi);
1338         return 0;
1339 }
1340
1341 static int matches_pack_name(struct packed_git *p, const char *ig)
1342 {
1343         const char *last_c, *c;
1344
1345         if (!strcmp(p->pack_name, ig))
1346                 return 0;
1347
1348         for (c = p->pack_name, last_c = c; *c;)
1349                 if (*c == '/')
1350                         last_c = ++c;
1351                 else
1352                         ++c;
1353         if (!strcmp(last_c, ig))
1354                 return 0;
1355
1356         return 1;
1357 }
1358
1359 static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1360 {
1361         struct packed_git *p;
1362         unsigned long offset;
1363
1364         prepare_packed_git();
1365
1366         for (p = packed_git; p; p = p->next) {
1367                 if (ignore_packed) {
1368                         const char **ig;
1369                         for (ig = ignore_packed; *ig; ig++)
1370                                 if (!matches_pack_name(p, *ig))
1371                                         break;
1372                         if (*ig)
1373                                 continue;
1374                 }
1375                 offset = find_pack_entry_one(sha1, p);
1376                 if (offset) {
1377                         e->offset = offset;
1378                         e->p = p;
1379                         hashcpy(e->sha1, sha1);
1380                         return 1;
1381                 }
1382         }
1383         return 0;
1384 }
1385
1386 struct packed_git *find_sha1_pack(const unsigned char *sha1,
1387                                   struct packed_git *packs)
1388 {
1389         struct packed_git *p;
1390
1391         for (p = packs; p; p = p->next) {
1392                 if (find_pack_entry_one(sha1, p))
1393                         return p;
1394         }
1395         return NULL;
1396
1397 }
1398
1399 static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1400 {
1401         int status;
1402         unsigned long mapsize, size;
1403         void *map;
1404         z_stream stream;
1405         char hdr[128];
1406
1407         map = map_sha1_file(sha1, &mapsize);
1408         if (!map)
1409                 return error("unable to find %s", sha1_to_hex(sha1));
1410         if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1411                 status = error("unable to unpack %s header",
1412                                sha1_to_hex(sha1));
1413         if (parse_sha1_header(hdr, type, &size) < 0)
1414                 status = error("unable to parse %s header", sha1_to_hex(sha1));
1415         else {
1416                 status = 0;
1417                 if (sizep)
1418                         *sizep = size;
1419         }
1420         inflateEnd(&stream);
1421         munmap(map, mapsize);
1422         return status;
1423 }
1424
1425 int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1426 {
1427         struct pack_entry e;
1428
1429         if (!find_pack_entry(sha1, &e, NULL)) {
1430                 reprepare_packed_git();
1431                 if (!find_pack_entry(sha1, &e, NULL))
1432                         return sha1_loose_object_info(sha1, type, sizep);
1433         }
1434         return packed_object_info(e.p, e.offset, type, sizep);
1435 }
1436
1437 static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1438 {
1439         struct pack_entry e;
1440
1441         if (!find_pack_entry(sha1, &e, NULL)) {
1442                 error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1443                 return NULL;
1444         }
1445         return unpack_entry(e.p, e.offset, type, size);
1446 }
1447
1448 void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1449 {
1450         unsigned long mapsize;
1451         void *map, *buf;
1452         struct pack_entry e;
1453
1454         if (find_pack_entry(sha1, &e, NULL))
1455                 return read_packed_sha1(sha1, type, size);
1456         map = map_sha1_file(sha1, &mapsize);
1457         if (map) {
1458                 buf = unpack_sha1_file(map, mapsize, type, size);
1459                 munmap(map, mapsize);
1460                 return buf;
1461         }
1462         reprepare_packed_git();
1463         if (find_pack_entry(sha1, &e, NULL))
1464                 return read_packed_sha1(sha1, type, size);
1465         return NULL;
1466 }
1467
1468 void *read_object_with_reference(const unsigned char *sha1,
1469                                  const char *required_type,
1470                                  unsigned long *size,
1471                                  unsigned char *actual_sha1_return)
1472 {
1473         char type[20];
1474         void *buffer;
1475         unsigned long isize;
1476         unsigned char actual_sha1[20];
1477
1478         hashcpy(actual_sha1, sha1);
1479         while (1) {
1480                 int ref_length = -1;
1481                 const char *ref_type = NULL;
1482
1483                 buffer = read_sha1_file(actual_sha1, type, &isize);
1484                 if (!buffer)
1485                         return NULL;
1486                 if (!strcmp(type, required_type)) {
1487                         *size = isize;
1488                         if (actual_sha1_return)
1489                                 hashcpy(actual_sha1_return, actual_sha1);
1490                         return buffer;
1491                 }
1492                 /* Handle references */
1493                 else if (!strcmp(type, commit_type))
1494                         ref_type = "tree ";
1495                 else if (!strcmp(type, tag_type))
1496                         ref_type = "object ";
1497                 else {
1498                         free(buffer);
1499                         return NULL;
1500                 }
1501                 ref_length = strlen(ref_type);
1502
1503                 if (memcmp(buffer, ref_type, ref_length) ||
1504                     get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1505                         free(buffer);
1506                         return NULL;
1507                 }
1508                 free(buffer);
1509                 /* Now we have the ID of the referred-to object in
1510                  * actual_sha1.  Check again. */
1511         }
1512 }
1513
1514 static void write_sha1_file_prepare(void *buf, unsigned long len,
1515                                     const char *type, unsigned char *sha1,
1516                                     unsigned char *hdr, int *hdrlen)
1517 {
1518         SHA_CTX c;
1519
1520         /* Generate the header */
1521         *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1522
1523         /* Sha1.. */
1524         SHA1_Init(&c);
1525         SHA1_Update(&c, hdr, *hdrlen);
1526         SHA1_Update(&c, buf, len);
1527         SHA1_Final(sha1, &c);
1528 }
1529
1530 /*
1531  * Link the tempfile to the final place, possibly creating the
1532  * last directory level as you do so.
1533  *
1534  * Returns the errno on failure, 0 on success.
1535  */
1536 static int link_temp_to_file(const char *tmpfile, const char *filename)
1537 {
1538         int ret;
1539         char *dir;
1540
1541         if (!link(tmpfile, filename))
1542                 return 0;
1543
1544         /*
1545          * Try to mkdir the last path component if that failed.
1546          *
1547          * Re-try the "link()" regardless of whether the mkdir
1548          * succeeds, since a race might mean that somebody
1549          * else succeeded.
1550          */
1551         ret = errno;
1552         dir = strrchr(filename, '/');
1553         if (dir) {
1554                 *dir = 0;
1555                 if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1556                         *dir = '/';
1557                         return -2;
1558                 }
1559                 *dir = '/';
1560                 if (!link(tmpfile, filename))
1561                         return 0;
1562                 ret = errno;
1563         }
1564         return ret;
1565 }
1566
1567 /*
1568  * Move the just written object into its final resting place
1569  */
1570 int move_temp_to_file(const char *tmpfile, const char *filename)
1571 {
1572         int ret = link_temp_to_file(tmpfile, filename);
1573
1574         /*
1575          * Coda hack - coda doesn't like cross-directory links,
1576          * so we fall back to a rename, which will mean that it
1577          * won't be able to check collisions, but that's not a
1578          * big deal.
1579          *
1580          * The same holds for FAT formatted media.
1581          *
1582          * When this succeeds, we just return 0. We have nothing
1583          * left to unlink.
1584          */
1585         if (ret && ret != EEXIST) {
1586                 if (!rename(tmpfile, filename))
1587                         return 0;
1588                 ret = errno;
1589         }
1590         unlink(tmpfile);
1591         if (ret) {
1592                 if (ret != EEXIST) {
1593                         return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1594                 }
1595                 /* FIXME!!! Collision check here ? */
1596         }
1597
1598         return 0;
1599 }
1600
1601 static int write_buffer(int fd, const void *buf, size_t len)
1602 {
1603         while (len) {
1604                 ssize_t size;
1605
1606                 size = write(fd, buf, len);
1607                 if (!size)
1608                         return error("file write: disk full");
1609                 if (size < 0) {
1610                         if (errno == EINTR || errno == EAGAIN)
1611                                 continue;
1612                         return error("file write error (%s)", strerror(errno));
1613                 }
1614                 len -= size;
1615                 buf = (char *) buf + size;
1616         }
1617         return 0;
1618 }
1619
1620 static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1621 {
1622         int hdr_len;
1623         unsigned char c;
1624
1625         c = (type << 4) | (len & 15);
1626         len >>= 4;
1627         hdr_len = 1;
1628         while (len) {
1629                 *hdr++ = c | 0x80;
1630                 hdr_len++;
1631                 c = (len & 0x7f);
1632                 len >>= 7;
1633         }
1634         *hdr = c;
1635         return hdr_len;
1636 }
1637
1638 static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1639 {
1640         int obj_type, hdr;
1641
1642         if (use_legacy_headers) {
1643                 while (deflate(stream, 0) == Z_OK)
1644                         /* nothing */;
1645                 return;
1646         }
1647         if (!strcmp(type, blob_type))
1648                 obj_type = OBJ_BLOB;
1649         else if (!strcmp(type, tree_type))
1650                 obj_type = OBJ_TREE;
1651         else if (!strcmp(type, commit_type))
1652                 obj_type = OBJ_COMMIT;
1653         else if (!strcmp(type, tag_type))
1654                 obj_type = OBJ_TAG;
1655         else
1656                 die("trying to generate bogus object of type '%s'", type);
1657         hdr = write_binary_header(stream->next_out, obj_type, len);
1658         stream->total_out = hdr;
1659         stream->next_out += hdr;
1660         stream->avail_out -= hdr;
1661 }
1662
1663 int hash_sha1_file(void *buf, unsigned long len, const char *type,
1664                    unsigned char *sha1)
1665 {
1666         unsigned char hdr[50];
1667         int hdrlen;
1668         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1669         return 0;
1670 }
1671
1672 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1673 {
1674         int size;
1675         unsigned char *compressed;
1676         z_stream stream;
1677         unsigned char sha1[20];
1678         char *filename;
1679         static char tmpfile[PATH_MAX];
1680         unsigned char hdr[50];
1681         int fd, hdrlen;
1682
1683         /* Normally if we have it in the pack then we do not bother writing
1684          * it out into .git/objects/??/?{38} file.
1685          */
1686         write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1687         filename = sha1_file_name(sha1);
1688         if (returnsha1)
1689                 hashcpy(returnsha1, sha1);
1690         if (has_sha1_file(sha1))
1691                 return 0;
1692         fd = open(filename, O_RDONLY);
1693         if (fd >= 0) {
1694                 /*
1695                  * FIXME!!! We might do collision checking here, but we'd
1696                  * need to uncompress the old file and check it. Later.
1697                  */
1698                 close(fd);
1699                 return 0;
1700         }
1701
1702         if (errno != ENOENT) {
1703                 return error("sha1 file %s: %s\n", filename, strerror(errno));
1704         }
1705
1706         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1707
1708         fd = mkstemp(tmpfile);
1709         if (fd < 0) {
1710                 if (errno == EPERM)
1711                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1712                 else
1713                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1714         }
1715
1716         /* Set it up */
1717         memset(&stream, 0, sizeof(stream));
1718         deflateInit(&stream, zlib_compression_level);
1719         size = 8 + deflateBound(&stream, len+hdrlen);
1720         compressed = xmalloc(size);
1721
1722         /* Compress it */
1723         stream.next_out = compressed;
1724         stream.avail_out = size;
1725
1726         /* First header.. */
1727         stream.next_in = hdr;
1728         stream.avail_in = hdrlen;
1729         setup_object_header(&stream, type, len);
1730
1731         /* Then the data itself.. */
1732         stream.next_in = buf;
1733         stream.avail_in = len;
1734         while (deflate(&stream, Z_FINISH) == Z_OK)
1735                 /* nothing */;
1736         deflateEnd(&stream);
1737         size = stream.total_out;
1738
1739         if (write_buffer(fd, compressed, size) < 0)
1740                 die("unable to write sha1 file");
1741         fchmod(fd, 0444);
1742         close(fd);
1743         free(compressed);
1744
1745         return move_temp_to_file(tmpfile, filename);
1746 }
1747
1748 /*
1749  * We need to unpack and recompress the object for writing
1750  * it out to a different file.
1751  */
1752 static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1753 {
1754         size_t size;
1755         z_stream stream;
1756         unsigned char *unpacked;
1757         unsigned long len;
1758         char type[20];
1759         char hdr[50];
1760         int hdrlen;
1761         void *buf;
1762
1763         /* need to unpack and recompress it by itself */
1764         unpacked = read_packed_sha1(sha1, type, &len);
1765
1766         hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1767
1768         /* Set it up */
1769         memset(&stream, 0, sizeof(stream));
1770         deflateInit(&stream, zlib_compression_level);
1771         size = deflateBound(&stream, len + hdrlen);
1772         buf = xmalloc(size);
1773
1774         /* Compress it */
1775         stream.next_out = buf;
1776         stream.avail_out = size;
1777
1778         /* First header.. */
1779         stream.next_in = (void *)hdr;
1780         stream.avail_in = hdrlen;
1781         while (deflate(&stream, 0) == Z_OK)
1782                 /* nothing */;
1783
1784         /* Then the data itself.. */
1785         stream.next_in = unpacked;
1786         stream.avail_in = len;
1787         while (deflate(&stream, Z_FINISH) == Z_OK)
1788                 /* nothing */;
1789         deflateEnd(&stream);
1790         free(unpacked);
1791
1792         *objsize = stream.total_out;
1793         return buf;
1794 }
1795
1796 int write_sha1_to_fd(int fd, const unsigned char *sha1)
1797 {
1798         int retval;
1799         unsigned long objsize;
1800         void *buf = map_sha1_file(sha1, &objsize);
1801
1802         if (buf) {
1803                 retval = write_buffer(fd, buf, objsize);
1804                 munmap(buf, objsize);
1805                 return retval;
1806         }
1807
1808         buf = repack_object(sha1, &objsize);
1809         retval = write_buffer(fd, buf, objsize);
1810         free(buf);
1811         return retval;
1812 }
1813
1814 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1815                        size_t bufsize, size_t *bufposn)
1816 {
1817         char tmpfile[PATH_MAX];
1818         int local;
1819         z_stream stream;
1820         unsigned char real_sha1[20];
1821         unsigned char discard[4096];
1822         int ret;
1823         SHA_CTX c;
1824
1825         snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1826
1827         local = mkstemp(tmpfile);
1828         if (local < 0) {
1829                 if (errno == EPERM)
1830                         return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1831                 else
1832                         return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1833         }
1834
1835         memset(&stream, 0, sizeof(stream));
1836
1837         inflateInit(&stream);
1838
1839         SHA1_Init(&c);
1840
1841         do {
1842                 ssize_t size;
1843                 if (*bufposn) {
1844                         stream.avail_in = *bufposn;
1845                         stream.next_in = (unsigned char *) buffer;
1846                         do {
1847                                 stream.next_out = discard;
1848                                 stream.avail_out = sizeof(discard);
1849                                 ret = inflate(&stream, Z_SYNC_FLUSH);
1850                                 SHA1_Update(&c, discard, sizeof(discard) -
1851                                             stream.avail_out);
1852                         } while (stream.avail_in && ret == Z_OK);
1853                         if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1854                                 die("unable to write sha1 file");
1855                         memmove(buffer, buffer + *bufposn - stream.avail_in,
1856                                 stream.avail_in);
1857                         *bufposn = stream.avail_in;
1858                         if (ret != Z_OK)
1859                                 break;
1860                 }
1861                 size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1862                 if (size <= 0) {
1863                         close(local);
1864                         unlink(tmpfile);
1865                         if (!size)
1866                                 return error("Connection closed?");
1867                         perror("Reading from connection");
1868                         return -1;
1869                 }
1870                 *bufposn += size;
1871         } while (1);
1872         inflateEnd(&stream);
1873
1874         close(local);
1875         SHA1_Final(real_sha1, &c);
1876         if (ret != Z_STREAM_END) {
1877                 unlink(tmpfile);
1878                 return error("File %s corrupted", sha1_to_hex(sha1));
1879         }
1880         if (hashcmp(sha1, real_sha1)) {
1881                 unlink(tmpfile);
1882                 return error("File %s has bad hash", sha1_to_hex(sha1));
1883         }
1884
1885         return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1886 }
1887
1888 int has_pack_index(const unsigned char *sha1)
1889 {
1890         struct stat st;
1891         if (stat(sha1_pack_index_name(sha1), &st))
1892                 return 0;
1893         return 1;
1894 }
1895
1896 int has_pack_file(const unsigned char *sha1)
1897 {
1898         struct stat st;
1899         if (stat(sha1_pack_name(sha1), &st))
1900                 return 0;
1901         return 1;
1902 }
1903
1904 int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1905 {
1906         struct pack_entry e;
1907         return find_pack_entry(sha1, &e, ignore_packed);
1908 }
1909
1910 int has_sha1_file(const unsigned char *sha1)
1911 {
1912         struct stat st;
1913         struct pack_entry e;
1914
1915         if (find_pack_entry(sha1, &e, NULL))
1916                 return 1;
1917         return find_sha1_file(sha1, &st) ? 1 : 0;
1918 }
1919
1920 /*
1921  * reads from fd as long as possible into a supplied buffer of size bytes.
1922  * If necessary the buffer's size is increased using realloc()
1923  *
1924  * returns 0 if anything went fine and -1 otherwise
1925  *
1926  * NOTE: both buf and size may change, but even when -1 is returned
1927  * you still have to free() it yourself.
1928  */
1929 int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1930 {
1931         char* buf = *return_buf;
1932         unsigned long size = *return_size;
1933         int iret;
1934         unsigned long off = 0;
1935
1936         do {
1937                 iret = xread(fd, buf + off, size - off);
1938                 if (iret > 0) {
1939                         off += iret;
1940                         if (off == size) {
1941                                 size *= 2;
1942                                 buf = xrealloc(buf, size);
1943                         }
1944                 }
1945         } while (iret > 0);
1946
1947         *return_buf = buf;
1948         *return_size = off;
1949
1950         if (iret < 0)
1951                 return -1;
1952         return 0;
1953 }
1954
1955 int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1956 {
1957         unsigned long size = 4096;
1958         char *buf = xmalloc(size);
1959         int ret;
1960
1961         if (read_pipe(fd, &buf, &size)) {
1962                 free(buf);
1963                 return -1;
1964         }
1965
1966         if (!type)
1967                 type = blob_type;
1968         if (write_object)
1969                 ret = write_sha1_file(buf, size, type, sha1);
1970         else
1971                 ret = hash_sha1_file(buf, size, type, sha1);
1972         free(buf);
1973         return ret;
1974 }
1975
1976 int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1977 {
1978         unsigned long size = st->st_size;
1979         void *buf;
1980         int ret;
1981
1982         buf = "";
1983         if (size)
1984                 buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1985         close(fd);
1986
1987         if (!type)
1988                 type = blob_type;
1989         if (write_object)
1990                 ret = write_sha1_file(buf, size, type, sha1);
1991         else
1992                 ret = hash_sha1_file(buf, size, type, sha1);
1993         if (size)
1994                 munmap(buf, size);
1995         return ret;
1996 }
1997
1998 int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1999 {
2000         int fd;
2001         char *target;
2002
2003         switch (st->st_mode & S_IFMT) {
2004         case S_IFREG:
2005                 fd = open(path, O_RDONLY);
2006                 if (fd < 0)
2007                         return error("open(\"%s\"): %s", path,
2008                                      strerror(errno));
2009                 if (index_fd(sha1, fd, st, write_object, NULL) < 0)
2010                         return error("%s: failed to insert into database",
2011                                      path);
2012                 break;
2013         case S_IFLNK:
2014                 target = xmalloc(st->st_size+1);
2015                 if (readlink(path, target, st->st_size+1) != st->st_size) {
2016                         char *errstr = strerror(errno);
2017                         free(target);
2018                         return error("readlink(\"%s\"): %s", path,
2019                                      errstr);
2020                 }
2021                 if (!write_object)
2022                         hash_sha1_file(target, st->st_size, blob_type, sha1);
2023                 else if (write_sha1_file(target, st->st_size, blob_type, sha1))
2024                         return error("%s: failed to insert into database",
2025                                      path);
2026                 free(target);
2027                 break;
2028         default:
2029                 return error("%s: unsupported file type", path);
2030         }
2031         return 0;
2032 }