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