sha1_file.con commit Merge branch 'jb/per-user-exclude' (c746e44)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 *
   6 * This handles basic git sha1 object files - packing, unpacking,
   7 * creation etc.
   8 */
   9#include "cache.h"
  10#include "delta.h"
  11#include "pack.h"
  12#include "blob.h"
  13#include "commit.h"
  14#include "tag.h"
  15#include "tree.h"
  16
  17#ifndef O_NOATIME
  18#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
  19#define O_NOATIME 01000000
  20#else
  21#define O_NOATIME 0
  22#endif
  23#endif
  24
  25#ifdef NO_C99_FORMAT
  26#define SZ_FMT "lu"
  27#else
  28#define SZ_FMT "zu"
  29#endif
  30
  31const unsigned char null_sha1[20];
  32
  33static unsigned int sha1_file_open_flag = O_NOATIME;
  34
  35signed char hexval_table[256] = {
  36         -1, -1, -1, -1, -1, -1, -1, -1,                /* 00-07 */
  37         -1, -1, -1, -1, -1, -1, -1, -1,                /* 08-0f */
  38         -1, -1, -1, -1, -1, -1, -1, -1,                /* 10-17 */
  39         -1, -1, -1, -1, -1, -1, -1, -1,                /* 18-1f */
  40         -1, -1, -1, -1, -1, -1, -1, -1,                /* 20-27 */
  41         -1, -1, -1, -1, -1, -1, -1, -1,                /* 28-2f */
  42          0,  1,  2,  3,  4,  5,  6,  7,                /* 30-37 */
  43          8,  9, -1, -1, -1, -1, -1, -1,                /* 38-3f */
  44         -1, 10, 11, 12, 13, 14, 15, -1,                /* 40-47 */
  45         -1, -1, -1, -1, -1, -1, -1, -1,                /* 48-4f */
  46         -1, -1, -1, -1, -1, -1, -1, -1,                /* 50-57 */
  47         -1, -1, -1, -1, -1, -1, -1, -1,                /* 58-5f */
  48         -1, 10, 11, 12, 13, 14, 15, -1,                /* 60-67 */
  49         -1, -1, -1, -1, -1, -1, -1, -1,                /* 68-67 */
  50         -1, -1, -1, -1, -1, -1, -1, -1,                /* 70-77 */
  51         -1, -1, -1, -1, -1, -1, -1, -1,                /* 78-7f */
  52         -1, -1, -1, -1, -1, -1, -1, -1,                /* 80-87 */
  53         -1, -1, -1, -1, -1, -1, -1, -1,                /* 88-8f */
  54         -1, -1, -1, -1, -1, -1, -1, -1,                /* 90-97 */
  55         -1, -1, -1, -1, -1, -1, -1, -1,                /* 98-9f */
  56         -1, -1, -1, -1, -1, -1, -1, -1,                /* a0-a7 */
  57         -1, -1, -1, -1, -1, -1, -1, -1,                /* a8-af */
  58         -1, -1, -1, -1, -1, -1, -1, -1,                /* b0-b7 */
  59         -1, -1, -1, -1, -1, -1, -1, -1,                /* b8-bf */
  60         -1, -1, -1, -1, -1, -1, -1, -1,                /* c0-c7 */
  61         -1, -1, -1, -1, -1, -1, -1, -1,                /* c8-cf */
  62         -1, -1, -1, -1, -1, -1, -1, -1,                /* d0-d7 */
  63         -1, -1, -1, -1, -1, -1, -1, -1,                /* d8-df */
  64         -1, -1, -1, -1, -1, -1, -1, -1,                /* e0-e7 */
  65         -1, -1, -1, -1, -1, -1, -1, -1,                /* e8-ef */
  66         -1, -1, -1, -1, -1, -1, -1, -1,                /* f0-f7 */
  67         -1, -1, -1, -1, -1, -1, -1, -1,                /* f8-ff */
  68};
  69
  70int get_sha1_hex(const char *hex, unsigned char *sha1)
  71{
  72        int i;
  73        for (i = 0; i < 20; i++) {
  74                unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
  75                if (val & ~0xff)
  76                        return -1;
  77                *sha1++ = val;
  78                hex += 2;
  79        }
  80        return 0;
  81}
  82
  83int safe_create_leading_directories(char *path)
  84{
  85        char *pos = path;
  86        struct stat st;
  87
  88        if (*pos == '/')
  89                pos++;
  90
  91        while (pos) {
  92                pos = strchr(pos, '/');
  93                if (!pos)
  94                        break;
  95                *pos = 0;
  96                if (!stat(path, &st)) {
  97                        /* path exists */
  98                        if (!S_ISDIR(st.st_mode)) {
  99                                *pos = '/';
 100                                return -3;
 101                        }
 102                }
 103                else if (mkdir(path, 0777)) {
 104                        *pos = '/';
 105                        return -1;
 106                }
 107                else if (adjust_shared_perm(path)) {
 108                        *pos = '/';
 109                        return -2;
 110                }
 111                *pos++ = '/';
 112        }
 113        return 0;
 114}
 115
 116char * sha1_to_hex(const unsigned char *sha1)
 117{
 118        static int bufno;
 119        static char hexbuffer[4][50];
 120        static const char hex[] = "0123456789abcdef";
 121        char *buffer = hexbuffer[3 & ++bufno], *buf = buffer;
 122        int i;
 123
 124        for (i = 0; i < 20; i++) {
 125                unsigned int val = *sha1++;
 126                *buf++ = hex[val >> 4];
 127                *buf++ = hex[val & 0xf];
 128        }
 129        *buf = '\0';
 130
 131        return buffer;
 132}
 133
 134static void fill_sha1_path(char *pathbuf, const unsigned char *sha1)
 135{
 136        int i;
 137        for (i = 0; i < 20; i++) {
 138                static char hex[] = "0123456789abcdef";
 139                unsigned int val = sha1[i];
 140                char *pos = pathbuf + i*2 + (i > 0);
 141                *pos++ = hex[val >> 4];
 142                *pos = hex[val & 0xf];
 143        }
 144}
 145
 146/*
 147 * NOTE! This returns a statically allocated buffer, so you have to be
 148 * careful about using it. Do a "xstrdup()" if you need to save the
 149 * filename.
 150 *
 151 * Also note that this returns the location for creating.  Reading
 152 * SHA1 file can happen from any alternate directory listed in the
 153 * DB_ENVIRONMENT environment variable if it is not found in
 154 * the primary object database.
 155 */
 156char *sha1_file_name(const unsigned char *sha1)
 157{
 158        static char *name, *base;
 159
 160        if (!base) {
 161                const char *sha1_file_directory = get_object_directory();
 162                int len = strlen(sha1_file_directory);
 163                base = xmalloc(len + 60);
 164                memcpy(base, sha1_file_directory, len);
 165                memset(base+len, 0, 60);
 166                base[len] = '/';
 167                base[len+3] = '/';
 168                name = base + len + 1;
 169        }
 170        fill_sha1_path(name, sha1);
 171        return base;
 172}
 173
 174char *sha1_pack_name(const unsigned char *sha1)
 175{
 176        static const char hex[] = "0123456789abcdef";
 177        static char *name, *base, *buf;
 178        int i;
 179
 180        if (!base) {
 181                const char *sha1_file_directory = get_object_directory();
 182                int len = strlen(sha1_file_directory);
 183                base = xmalloc(len + 60);
 184                sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.pack", sha1_file_directory);
 185                name = base + len + 11;
 186        }
 187
 188        buf = name;
 189
 190        for (i = 0; i < 20; i++) {
 191                unsigned int val = *sha1++;
 192                *buf++ = hex[val >> 4];
 193                *buf++ = hex[val & 0xf];
 194        }
 195        
 196        return base;
 197}
 198
 199char *sha1_pack_index_name(const unsigned char *sha1)
 200{
 201        static const char hex[] = "0123456789abcdef";
 202        static char *name, *base, *buf;
 203        int i;
 204
 205        if (!base) {
 206                const char *sha1_file_directory = get_object_directory();
 207                int len = strlen(sha1_file_directory);
 208                base = xmalloc(len + 60);
 209                sprintf(base, "%s/pack/pack-1234567890123456789012345678901234567890.idx", sha1_file_directory);
 210                name = base + len + 11;
 211        }
 212
 213        buf = name;
 214
 215        for (i = 0; i < 20; i++) {
 216                unsigned int val = *sha1++;
 217                *buf++ = hex[val >> 4];
 218                *buf++ = hex[val & 0xf];
 219        }
 220        
 221        return base;
 222}
 223
 224struct alternate_object_database *alt_odb_list;
 225static struct alternate_object_database **alt_odb_tail;
 226
 227static void read_info_alternates(const char * alternates, int depth);
 228
 229/*
 230 * Prepare alternate object database registry.
 231 *
 232 * The variable alt_odb_list points at the list of struct
 233 * alternate_object_database.  The elements on this list come from
 234 * non-empty elements from colon separated ALTERNATE_DB_ENVIRONMENT
 235 * environment variable, and $GIT_OBJECT_DIRECTORY/info/alternates,
 236 * whose contents is similar to that environment variable but can be
 237 * LF separated.  Its base points at a statically allocated buffer that
 238 * contains "/the/directory/corresponding/to/.git/objects/...", while
 239 * its name points just after the slash at the end of ".git/objects/"
 240 * in the example above, and has enough space to hold 40-byte hex
 241 * SHA1, an extra slash for the first level indirection, and the
 242 * terminating NUL.
 243 */
 244static int link_alt_odb_entry(const char * entry, int len, const char * relative_base, int depth)
 245{
 246        struct stat st;
 247        const char *objdir = get_object_directory();
 248        struct alternate_object_database *ent;
 249        struct alternate_object_database *alt;
 250        /* 43 = 40-byte + 2 '/' + terminating NUL */
 251        int pfxlen = len;
 252        int entlen = pfxlen + 43;
 253        int base_len = -1;
 254
 255        if (*entry != '/' && relative_base) {
 256                /* Relative alt-odb */
 257                if (base_len < 0)
 258                        base_len = strlen(relative_base) + 1;
 259                entlen += base_len;
 260                pfxlen += base_len;
 261        }
 262        ent = xmalloc(sizeof(*ent) + entlen);
 263
 264        if (*entry != '/' && relative_base) {
 265                memcpy(ent->base, relative_base, base_len - 1);
 266                ent->base[base_len - 1] = '/';
 267                memcpy(ent->base + base_len, entry, len);
 268        }
 269        else
 270                memcpy(ent->base, entry, pfxlen);
 271
 272        ent->name = ent->base + pfxlen + 1;
 273        ent->base[pfxlen + 3] = '/';
 274        ent->base[pfxlen] = ent->base[entlen-1] = 0;
 275
 276        /* Detect cases where alternate disappeared */
 277        if (stat(ent->base, &st) || !S_ISDIR(st.st_mode)) {
 278                error("object directory %s does not exist; "
 279                      "check .git/objects/info/alternates.",
 280                      ent->base);
 281                free(ent);
 282                return -1;
 283        }
 284
 285        /* Prevent the common mistake of listing the same
 286         * thing twice, or object directory itself.
 287         */
 288        for (alt = alt_odb_list; alt; alt = alt->next) {
 289                if (!memcmp(ent->base, alt->base, pfxlen)) {
 290                        free(ent);
 291                        return -1;
 292                }
 293        }
 294        if (!memcmp(ent->base, objdir, pfxlen)) {
 295                free(ent);
 296                return -1;
 297        }
 298
 299        /* add the alternate entry */
 300        *alt_odb_tail = ent;
 301        alt_odb_tail = &(ent->next);
 302        ent->next = NULL;
 303
 304        /* recursively add alternates */
 305        read_info_alternates(ent->base, depth + 1);
 306
 307        ent->base[pfxlen] = '/';
 308
 309        return 0;
 310}
 311
 312static void link_alt_odb_entries(const char *alt, const char *ep, int sep,
 313                                 const char *relative_base, int depth)
 314{
 315        const char *cp, *last;
 316
 317        if (depth > 5) {
 318                error("%s: ignoring alternate object stores, nesting too deep.",
 319                                relative_base);
 320                return;
 321        }
 322
 323        last = alt;
 324        while (last < ep) {
 325                cp = last;
 326                if (cp < ep && *cp == '#') {
 327                        while (cp < ep && *cp != sep)
 328                                cp++;
 329                        last = cp + 1;
 330                        continue;
 331                }
 332                while (cp < ep && *cp != sep)
 333                        cp++;
 334                if (last != cp) {
 335                        if ((*last != '/') && depth) {
 336                                error("%s: ignoring relative alternate object store %s",
 337                                                relative_base, last);
 338                        } else {
 339                                link_alt_odb_entry(last, cp - last,
 340                                                relative_base, depth);
 341                        }
 342                }
 343                while (cp < ep && *cp == sep)
 344                        cp++;
 345                last = cp;
 346        }
 347}
 348
 349static void read_info_alternates(const char * relative_base, int depth)
 350{
 351        char *map;
 352        size_t mapsz;
 353        struct stat st;
 354        char path[PATH_MAX];
 355        int fd;
 356
 357        sprintf(path, "%s/info/alternates", relative_base);
 358        fd = open(path, O_RDONLY);
 359        if (fd < 0)
 360                return;
 361        if (fstat(fd, &st) || (st.st_size == 0)) {
 362                close(fd);
 363                return;
 364        }
 365        mapsz = xsize_t(st.st_size);
 366        map = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, fd, 0);
 367        close(fd);
 368
 369        link_alt_odb_entries(map, map + mapsz, '\n', relative_base, depth);
 370
 371        munmap(map, mapsz);
 372}
 373
 374void prepare_alt_odb(void)
 375{
 376        const char *alt;
 377
 378        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 379        if (!alt) alt = "";
 380
 381        if (alt_odb_tail)
 382                return;
 383        alt_odb_tail = &alt_odb_list;
 384        link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 385
 386        read_info_alternates(get_object_directory(), 0);
 387}
 388
 389static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 390{
 391        char *name = sha1_file_name(sha1);
 392        struct alternate_object_database *alt;
 393
 394        if (!stat(name, st))
 395                return name;
 396        prepare_alt_odb();
 397        for (alt = alt_odb_list; alt; alt = alt->next) {
 398                name = alt->name;
 399                fill_sha1_path(name, sha1);
 400                if (!stat(alt->base, st))
 401                        return alt->base;
 402        }
 403        return NULL;
 404}
 405
 406static unsigned int pack_used_ctr;
 407static unsigned int pack_mmap_calls;
 408static unsigned int peak_pack_open_windows;
 409static unsigned int pack_open_windows;
 410static size_t peak_pack_mapped;
 411static size_t pack_mapped;
 412struct packed_git *packed_git;
 413
 414void pack_report()
 415{
 416        fprintf(stderr,
 417                "pack_report: getpagesize()            = %10" SZ_FMT "\n"
 418                "pack_report: core.packedGitWindowSize = %10" SZ_FMT "\n"
 419                "pack_report: core.packedGitLimit      = %10" SZ_FMT "\n",
 420                (size_t) getpagesize(),
 421                packed_git_window_size,
 422                packed_git_limit);
 423        fprintf(stderr,
 424                "pack_report: pack_used_ctr            = %10u\n"
 425                "pack_report: pack_mmap_calls          = %10u\n"
 426                "pack_report: pack_open_windows        = %10u / %10u\n"
 427                "pack_report: pack_mapped              = "
 428                        "%10" SZ_FMT " / %10" SZ_FMT "\n",
 429                pack_used_ctr,
 430                pack_mmap_calls,
 431                pack_open_windows, peak_pack_open_windows,
 432                pack_mapped, peak_pack_mapped);
 433}
 434
 435static int check_packed_git_idx(const char *path,
 436        unsigned long *idx_size_,
 437        void **idx_map_)
 438{
 439        void *idx_map;
 440        uint32_t *index;
 441        size_t idx_size;
 442        uint32_t nr, i;
 443        int fd = open(path, O_RDONLY);
 444        struct stat st;
 445        if (fd < 0)
 446                return -1;
 447        if (fstat(fd, &st)) {
 448                close(fd);
 449                return -1;
 450        }
 451        idx_size = xsize_t(st.st_size);
 452        if (idx_size < 4 * 256 + 20 + 20) {
 453                close(fd);
 454                return error("index file %s is too small", path);
 455        }
 456        idx_map = xmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 457        close(fd);
 458
 459        index = idx_map;
 460        *idx_map_ = idx_map;
 461        *idx_size_ = idx_size;
 462
 463        /* a future index format would start with this, as older git
 464         * binaries would fail the non-monotonic index check below.
 465         * give a nicer warning to the user if we can.
 466         */
 467        if (index[0] == htonl(PACK_IDX_SIGNATURE)) {
 468                munmap(idx_map, idx_size);
 469                return error("index file %s is a newer version"
 470                        " and is not supported by this binary"
 471                        " (try upgrading GIT to a newer version)",
 472                        path);
 473        }
 474
 475        nr = 0;
 476        for (i = 0; i < 256; i++) {
 477                uint32_t n = ntohl(index[i]);
 478                if (n < nr) {
 479                        munmap(idx_map, idx_size);
 480                        return error("non-monotonic index %s", path);
 481                }
 482                nr = n;
 483        }
 484
 485        /*
 486         * Total size:
 487         *  - 256 index entries 4 bytes each
 488         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 489         *  - 20-byte SHA1 of the packfile
 490         *  - 20-byte SHA1 file checksum
 491         */
 492        if (idx_size != 4*256 + nr * 24 + 20 + 20) {
 493                munmap(idx_map, idx_size);
 494                return error("wrong index file size in %s", path);
 495        }
 496
 497        return 0;
 498}
 499
 500static void scan_windows(struct packed_git *p,
 501        struct packed_git **lru_p,
 502        struct pack_window **lru_w,
 503        struct pack_window **lru_l)
 504{
 505        struct pack_window *w, *w_l;
 506
 507        for (w_l = NULL, w = p->windows; w; w = w->next) {
 508                if (!w->inuse_cnt) {
 509                        if (!*lru_w || w->last_used < (*lru_w)->last_used) {
 510                                *lru_p = p;
 511                                *lru_w = w;
 512                                *lru_l = w_l;
 513                        }
 514                }
 515                w_l = w;
 516        }
 517}
 518
 519static int unuse_one_window(struct packed_git *current)
 520{
 521        struct packed_git *p, *lru_p = NULL;
 522        struct pack_window *lru_w = NULL, *lru_l = NULL;
 523
 524        if (current)
 525                scan_windows(current, &lru_p, &lru_w, &lru_l);
 526        for (p = packed_git; p; p = p->next)
 527                scan_windows(p, &lru_p, &lru_w, &lru_l);
 528        if (lru_p) {
 529                munmap(lru_w->base, lru_w->len);
 530                pack_mapped -= lru_w->len;
 531                if (lru_l)
 532                        lru_l->next = lru_w->next;
 533                else {
 534                        lru_p->windows = lru_w->next;
 535                        if (!lru_p->windows && lru_p != current) {
 536                                close(lru_p->pack_fd);
 537                                lru_p->pack_fd = -1;
 538                        }
 539                }
 540                free(lru_w);
 541                pack_open_windows--;
 542                return 1;
 543        }
 544        return 0;
 545}
 546
 547void release_pack_memory(size_t need)
 548{
 549        size_t cur = pack_mapped;
 550        while (need >= (cur - pack_mapped) && unuse_one_window(NULL))
 551                ; /* nothing */
 552}
 553
 554void unuse_pack(struct pack_window **w_cursor)
 555{
 556        struct pack_window *w = *w_cursor;
 557        if (w) {
 558                w->inuse_cnt--;
 559                *w_cursor = NULL;
 560        }
 561}
 562
 563/*
 564 * Do not call this directly as this leaks p->pack_fd on error return;
 565 * call open_packed_git() instead.
 566 */
 567static int open_packed_git_1(struct packed_git *p)
 568{
 569        struct stat st;
 570        struct pack_header hdr;
 571        unsigned char sha1[20];
 572        unsigned char *idx_sha1;
 573        long fd_flag;
 574
 575        p->pack_fd = open(p->pack_name, O_RDONLY);
 576        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 577                return -1;
 578
 579        /* If we created the struct before we had the pack we lack size. */
 580        if (!p->pack_size) {
 581                if (!S_ISREG(st.st_mode))
 582                        return error("packfile %s not a regular file", p->pack_name);
 583                p->pack_size = st.st_size;
 584        } else if (p->pack_size != st.st_size)
 585                return error("packfile %s size changed", p->pack_name);
 586
 587        /* We leave these file descriptors open with sliding mmap;
 588         * there is no point keeping them open across exec(), though.
 589         */
 590        fd_flag = fcntl(p->pack_fd, F_GETFD, 0);
 591        if (fd_flag < 0)
 592                return error("cannot determine file descriptor flags");
 593        fd_flag |= FD_CLOEXEC;
 594        if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1)
 595                return error("cannot set FD_CLOEXEC");
 596
 597        /* Verify we recognize this pack file format. */
 598        if (read_in_full(p->pack_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
 599                return error("file %s is far too short to be a packfile", p->pack_name);
 600        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 601                return error("file %s is not a GIT packfile", p->pack_name);
 602        if (!pack_version_ok(hdr.hdr_version))
 603                return error("packfile %s is version %u and not supported"
 604                        " (try upgrading GIT to a newer version)",
 605                        p->pack_name, ntohl(hdr.hdr_version));
 606
 607        /* Verify the pack matches its index. */
 608        if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 609                return error("packfile %s claims to have %u objects"
 610                        " while index size indicates %u objects",
 611                        p->pack_name, ntohl(hdr.hdr_entries),
 612                        num_packed_objects(p));
 613        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 614                return error("end of packfile %s is unavailable", p->pack_name);
 615        if (read_in_full(p->pack_fd, sha1, sizeof(sha1)) != sizeof(sha1))
 616                return error("packfile %s signature is unavailable", p->pack_name);
 617        idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 618        if (hashcmp(sha1, idx_sha1))
 619                return error("packfile %s does not match index", p->pack_name);
 620        return 0;
 621}
 622
 623static int open_packed_git(struct packed_git *p)
 624{
 625        if (!open_packed_git_1(p))
 626                return 0;
 627        if (p->pack_fd != -1) {
 628                close(p->pack_fd);
 629                p->pack_fd = -1;
 630        }
 631        return -1;
 632}
 633
 634static int in_window(struct pack_window *win, off_t offset)
 635{
 636        /* We must promise at least 20 bytes (one hash) after the
 637         * offset is available from this window, otherwise the offset
 638         * is not actually in this window and a different window (which
 639         * has that one hash excess) must be used.  This is to support
 640         * the object header and delta base parsing routines below.
 641         */
 642        off_t win_off = win->offset;
 643        return win_off <= offset
 644                && (offset + 20) <= (win_off + win->len);
 645}
 646
 647unsigned char* use_pack(struct packed_git *p,
 648                struct pack_window **w_cursor,
 649                off_t offset,
 650                unsigned int *left)
 651{
 652        struct pack_window *win = *w_cursor;
 653
 654        if (p->pack_fd == -1 && open_packed_git(p))
 655                die("packfile %s cannot be accessed", p->pack_name);
 656
 657        /* Since packfiles end in a hash of their content and its
 658         * pointless to ask for an offset into the middle of that
 659         * hash, and the in_window function above wouldn't match
 660         * don't allow an offset too close to the end of the file.
 661         */
 662        if (offset > (p->pack_size - 20))
 663                die("offset beyond end of packfile (truncated pack?)");
 664
 665        if (!win || !in_window(win, offset)) {
 666                if (win)
 667                        win->inuse_cnt--;
 668                for (win = p->windows; win; win = win->next) {
 669                        if (in_window(win, offset))
 670                                break;
 671                }
 672                if (!win) {
 673                        size_t window_align = packed_git_window_size / 2;
 674                        off_t len;
 675                        win = xcalloc(1, sizeof(*win));
 676                        win->offset = (offset / window_align) * window_align;
 677                        len = p->pack_size - win->offset;
 678                        if (len > packed_git_window_size)
 679                                len = packed_git_window_size;
 680                        win->len = (size_t)len;
 681                        pack_mapped += win->len;
 682                        while (packed_git_limit < pack_mapped
 683                                && unuse_one_window(p))
 684                                ; /* nothing */
 685                        win->base = xmmap(NULL, win->len,
 686                                PROT_READ, MAP_PRIVATE,
 687                                p->pack_fd, win->offset);
 688                        if (win->base == MAP_FAILED)
 689                                die("packfile %s cannot be mapped: %s",
 690                                        p->pack_name,
 691                                        strerror(errno));
 692                        pack_mmap_calls++;
 693                        pack_open_windows++;
 694                        if (pack_mapped > peak_pack_mapped)
 695                                peak_pack_mapped = pack_mapped;
 696                        if (pack_open_windows > peak_pack_open_windows)
 697                                peak_pack_open_windows = pack_open_windows;
 698                        win->next = p->windows;
 699                        p->windows = win;
 700                }
 701        }
 702        if (win != *w_cursor) {
 703                win->last_used = pack_used_ctr++;
 704                win->inuse_cnt++;
 705                *w_cursor = win;
 706        }
 707        offset -= win->offset;
 708        if (left)
 709                *left = win->len - xsize_t(offset);
 710        return win->base + offset;
 711}
 712
 713struct packed_git *add_packed_git(char *path, int path_len, int local)
 714{
 715        struct stat st;
 716        struct packed_git *p;
 717        unsigned long idx_size;
 718        void *idx_map;
 719        unsigned char sha1[20];
 720
 721        if (check_packed_git_idx(path, &idx_size, &idx_map))
 722                return NULL;
 723
 724        /* do we have a corresponding .pack file? */
 725        strcpy(path + path_len - 4, ".pack");
 726        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 727                munmap(idx_map, idx_size);
 728                return NULL;
 729        }
 730        /* ok, it looks sane as far as we can check without
 731         * actually mapping the pack file.
 732         */
 733        p = xmalloc(sizeof(*p) + path_len + 2);
 734        strcpy(p->pack_name, path);
 735        p->index_size = idx_size;
 736        p->pack_size = st.st_size;
 737        p->index_base = idx_map;
 738        p->next = NULL;
 739        p->windows = NULL;
 740        p->pack_fd = -1;
 741        p->pack_local = local;
 742        if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 743                hashcpy(p->sha1, sha1);
 744        return p;
 745}
 746
 747struct packed_git *parse_pack_index(unsigned char *sha1)
 748{
 749        char *path = sha1_pack_index_name(sha1);
 750        return parse_pack_index_file(sha1, path);
 751}
 752
 753struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 754{
 755        struct packed_git *p;
 756        unsigned long idx_size;
 757        void *idx_map;
 758        char *path;
 759
 760        if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 761                return NULL;
 762
 763        path = sha1_pack_name(sha1);
 764
 765        p = xmalloc(sizeof(*p) + strlen(path) + 2);
 766        strcpy(p->pack_name, path);
 767        p->index_size = idx_size;
 768        p->pack_size = 0;
 769        p->index_base = idx_map;
 770        p->next = NULL;
 771        p->windows = NULL;
 772        p->pack_fd = -1;
 773        hashcpy(p->sha1, sha1);
 774        return p;
 775}
 776
 777void install_packed_git(struct packed_git *pack)
 778{
 779        pack->next = packed_git;
 780        packed_git = pack;
 781}
 782
 783static void prepare_packed_git_one(char *objdir, int local)
 784{
 785        char path[PATH_MAX];
 786        int len;
 787        DIR *dir;
 788        struct dirent *de;
 789
 790        sprintf(path, "%s/pack", objdir);
 791        len = strlen(path);
 792        dir = opendir(path);
 793        if (!dir) {
 794                if (errno != ENOENT)
 795                        error("unable to open object pack directory: %s: %s",
 796                              path, strerror(errno));
 797                return;
 798        }
 799        path[len++] = '/';
 800        while ((de = readdir(dir)) != NULL) {
 801                int namelen = strlen(de->d_name);
 802                struct packed_git *p;
 803
 804                if (!has_extension(de->d_name, ".idx"))
 805                        continue;
 806
 807                /* Don't reopen a pack we already have. */
 808                strcpy(path + len, de->d_name);
 809                for (p = packed_git; p; p = p->next) {
 810                        if (!memcmp(path, p->pack_name, len + namelen - 4))
 811                                break;
 812                }
 813                if (p)
 814                        continue;
 815                /* See if it really is a valid .idx file with corresponding
 816                 * .pack file that we can map.
 817                 */
 818                p = add_packed_git(path, len + namelen, local);
 819                if (!p)
 820                        continue;
 821                install_packed_git(p);
 822        }
 823        closedir(dir);
 824}
 825
 826static int prepare_packed_git_run_once = 0;
 827void prepare_packed_git(void)
 828{
 829        struct alternate_object_database *alt;
 830
 831        if (prepare_packed_git_run_once)
 832                return;
 833        prepare_packed_git_one(get_object_directory(), 1);
 834        prepare_alt_odb();
 835        for (alt = alt_odb_list; alt; alt = alt->next) {
 836                alt->name[-1] = 0;
 837                prepare_packed_git_one(alt->base, 0);
 838                alt->name[-1] = '/';
 839        }
 840        prepare_packed_git_run_once = 1;
 841}
 842
 843void reprepare_packed_git(void)
 844{
 845        prepare_packed_git_run_once = 0;
 846        prepare_packed_git();
 847}
 848
 849int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 850{
 851        unsigned char real_sha1[20];
 852        hash_sha1_file(map, size, type, real_sha1);
 853        return hashcmp(sha1, real_sha1) ? -1 : 0;
 854}
 855
 856void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 857{
 858        struct stat st;
 859        void *map;
 860        int fd;
 861        char *filename = find_sha1_file(sha1, &st);
 862
 863        if (!filename) {
 864                return NULL;
 865        }
 866
 867        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 868        if (fd < 0) {
 869                /* See if it works without O_NOATIME */
 870                switch (sha1_file_open_flag) {
 871                default:
 872                        fd = open(filename, O_RDONLY);
 873                        if (fd >= 0)
 874                                break;
 875                /* Fallthrough */
 876                case 0:
 877                        return NULL;
 878                }
 879
 880                /* If it failed once, it will probably fail again.
 881                 * Stop using O_NOATIME
 882                 */
 883                sha1_file_open_flag = 0;
 884        }
 885        *size = xsize_t(st.st_size);
 886        map = xmmap(NULL, *size, PROT_READ, MAP_PRIVATE, fd, 0);
 887        close(fd);
 888        return map;
 889}
 890
 891int legacy_loose_object(unsigned char *map)
 892{
 893        unsigned int word;
 894
 895        /*
 896         * Is it a zlib-compressed buffer? If so, the first byte
 897         * must be 0x78 (15-bit window size, deflated), and the
 898         * first 16-bit word is evenly divisible by 31
 899         */
 900        word = (map[0] << 8) + map[1];
 901        if (map[0] == 0x78 && !(word % 31))
 902                return 1;
 903        else
 904                return 0;
 905}
 906
 907unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 908{
 909        unsigned shift;
 910        unsigned char c;
 911        unsigned long size;
 912        unsigned long used = 0;
 913
 914        c = buf[used++];
 915        *type = (c >> 4) & 7;
 916        size = c & 15;
 917        shift = 4;
 918        while (c & 0x80) {
 919                if (len <= used)
 920                        return 0;
 921                if (sizeof(long) * 8 <= shift)
 922                        return 0;
 923                c = buf[used++];
 924                size += (c & 0x7f) << shift;
 925                shift += 7;
 926        }
 927        *sizep = size;
 928        return used;
 929}
 930
 931static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 932{
 933        unsigned long size, used;
 934        static const char valid_loose_object_type[8] = {
 935                0, /* OBJ_EXT */
 936                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 937                0, /* "delta" and others are invalid in a loose object */
 938        };
 939        enum object_type type;
 940
 941        /* Get the data stream */
 942        memset(stream, 0, sizeof(*stream));
 943        stream->next_in = map;
 944        stream->avail_in = mapsize;
 945        stream->next_out = buffer;
 946        stream->avail_out = bufsiz;
 947
 948        if (legacy_loose_object(map)) {
 949                inflateInit(stream);
 950                return inflate(stream, 0);
 951        }
 952
 953        used = unpack_object_header_gently(map, mapsize, &type, &size);
 954        if (!used || !valid_loose_object_type[type])
 955                return -1;
 956        map += used;
 957        mapsize -= used;
 958
 959        /* Set up the stream for the rest.. */
 960        stream->next_in = map;
 961        stream->avail_in = mapsize;
 962        inflateInit(stream);
 963
 964        /* And generate the fake traditional header */
 965        stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 966                                         typename(type), size);
 967        return 0;
 968}
 969
 970static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size, const unsigned char *sha1)
 971{
 972        int bytes = strlen(buffer) + 1;
 973        unsigned char *buf = xmalloc(1+size);
 974        unsigned long n;
 975        int status = Z_OK;
 976
 977        n = stream->total_out - bytes;
 978        if (n > size)
 979                n = size;
 980        memcpy(buf, (char *) buffer + bytes, n);
 981        bytes = n;
 982        if (bytes < size) {
 983                stream->next_out = buf + bytes;
 984                stream->avail_out = size - bytes;
 985                while (status == Z_OK)
 986                        status = inflate(stream, Z_FINISH);
 987        }
 988        buf[size] = 0;
 989        if ((status == Z_OK || status == Z_STREAM_END) && !stream->avail_in) {
 990                inflateEnd(stream);
 991                return buf;
 992        }
 993
 994        if (status < 0)
 995                error("corrupt loose object '%s'", sha1_to_hex(sha1));
 996        else if (stream->avail_in)
 997                error("garbage at end of loose object '%s'",
 998                      sha1_to_hex(sha1));
 999        free(buf);
1000        return NULL;
1001}
1002
1003/*
1004 * We used to just use "sscanf()", but that's actually way
1005 * too permissive for what we want to check. So do an anal
1006 * object header parse by hand.
1007 */
1008static int parse_sha1_header(const char *hdr, unsigned long *sizep)
1009{
1010        char type[10];
1011        int i;
1012        unsigned long size;
1013
1014        /*
1015         * The type can be at most ten bytes (including the 
1016         * terminating '\0' that we add), and is followed by
1017         * a space.
1018         */
1019        i = 0;
1020        for (;;) {
1021                char c = *hdr++;
1022                if (c == ' ')
1023                        break;
1024                type[i++] = c;
1025                if (i >= sizeof(type))
1026                        return -1;
1027        }
1028        type[i] = 0;
1029
1030        /*
1031         * The length must follow immediately, and be in canonical
1032         * decimal format (ie "010" is not valid).
1033         */
1034        size = *hdr++ - '0';
1035        if (size > 9)
1036                return -1;
1037        if (size) {
1038                for (;;) {
1039                        unsigned long c = *hdr - '0';
1040                        if (c > 9)
1041                                break;
1042                        hdr++;
1043                        size = size * 10 + c;
1044                }
1045        }
1046        *sizep = size;
1047
1048        /*
1049         * The length must be followed by a zero byte
1050         */
1051        return *hdr ? -1 : type_from_string(type);
1052}
1053
1054static void *unpack_sha1_file(void *map, unsigned long mapsize, enum object_type *type, unsigned long *size, const unsigned char *sha1)
1055{
1056        int ret;
1057        z_stream stream;
1058        char hdr[8192];
1059
1060        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
1061        if (ret < Z_OK || (*type = parse_sha1_header(hdr, size)) < 0)
1062                return NULL;
1063
1064        return unpack_sha1_rest(&stream, hdr, *size, sha1);
1065}
1066
1067static off_t get_delta_base(struct packed_git *p,
1068                                    struct pack_window **w_curs,
1069                                    off_t *curpos,
1070                                    enum object_type type,
1071                                    off_t delta_obj_offset)
1072{
1073        unsigned char *base_info = use_pack(p, w_curs, *curpos, NULL);
1074        off_t base_offset;
1075
1076        /* use_pack() assured us we have [base_info, base_info + 20)
1077         * as a range that we can look at without walking off the
1078         * end of the mapped window.  Its actually the hash size
1079         * that is assured.  An OFS_DELTA longer than the hash size
1080         * is stupid, as then a REF_DELTA would be smaller to store.
1081         */
1082        if (type == OBJ_OFS_DELTA) {
1083                unsigned used = 0;
1084                unsigned char c = base_info[used++];
1085                base_offset = c & 127;
1086                while (c & 128) {
1087                        base_offset += 1;
1088                        if (!base_offset || base_offset & ~(~0UL >> 7))
1089                                die("offset value overflow for delta base object");
1090                        c = base_info[used++];
1091                        base_offset = (base_offset << 7) + (c & 127);
1092                }
1093                base_offset = delta_obj_offset - base_offset;
1094                if (base_offset >= delta_obj_offset)
1095                        die("delta base offset out of bound");
1096                *curpos += used;
1097        } else if (type == OBJ_REF_DELTA) {
1098                /* The base entry _must_ be in the same pack */
1099                base_offset = find_pack_entry_one(base_info, p);
1100                if (!base_offset)
1101                        die("failed to find delta-pack base object %s",
1102                                sha1_to_hex(base_info));
1103                *curpos += 20;
1104        } else
1105                die("I am totally screwed");
1106        return base_offset;
1107}
1108
1109/* forward declaration for a mutually recursive function */
1110static int packed_object_info(struct packed_git *p, off_t offset,
1111                              unsigned long *sizep);
1112
1113static int packed_delta_info(struct packed_git *p,
1114                             struct pack_window **w_curs,
1115                             off_t curpos,
1116                             enum object_type type,
1117                             off_t obj_offset,
1118                             unsigned long *sizep)
1119{
1120        off_t base_offset;
1121
1122        base_offset = get_delta_base(p, w_curs, &curpos, type, obj_offset);
1123        type = packed_object_info(p, base_offset, NULL);
1124
1125        /* We choose to only get the type of the base object and
1126         * ignore potentially corrupt pack file that expects the delta
1127         * based on a base with a wrong size.  This saves tons of
1128         * inflate() calls.
1129         */
1130        if (sizep) {
1131                const unsigned char *data;
1132                unsigned char delta_head[20], *in;
1133                z_stream stream;
1134                int st;
1135
1136                memset(&stream, 0, sizeof(stream));
1137                stream.next_out = delta_head;
1138                stream.avail_out = sizeof(delta_head);
1139
1140                inflateInit(&stream);
1141                do {
1142                        in = use_pack(p, w_curs, curpos, &stream.avail_in);
1143                        stream.next_in = in;
1144                        st = inflate(&stream, Z_FINISH);
1145                        curpos += stream.next_in - in;
1146                } while ((st == Z_OK || st == Z_BUF_ERROR)
1147                        && stream.total_out < sizeof(delta_head));
1148                inflateEnd(&stream);
1149                if ((st != Z_STREAM_END) &&
1150                    stream.total_out != sizeof(delta_head))
1151                        die("delta data unpack-initial failed");
1152
1153                /* Examine the initial part of the delta to figure out
1154                 * the result size.
1155                 */
1156                data = delta_head;
1157
1158                /* ignore base size */
1159                get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1160
1161                /* Read the result size */
1162                *sizep = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1163        }
1164
1165        return type;
1166}
1167
1168static int unpack_object_header(struct packed_git *p,
1169                                struct pack_window **w_curs,
1170                                off_t *curpos,
1171                                unsigned long *sizep)
1172{
1173        unsigned char *base;
1174        unsigned int left;
1175        unsigned long used;
1176        enum object_type type;
1177
1178        /* use_pack() assures us we have [base, base + 20) available
1179         * as a range that we can look at at.  (Its actually the hash
1180         * size that is assured.)  With our object header encoding
1181         * the maximum deflated object size is 2^137, which is just
1182         * insane, so we know won't exceed what we have been given.
1183         */
1184        base = use_pack(p, w_curs, *curpos, &left);
1185        used = unpack_object_header_gently(base, left, &type, sizep);
1186        if (!used)
1187                die("object offset outside of pack file");
1188        *curpos += used;
1189
1190        return type;
1191}
1192
1193const char *packed_object_info_detail(struct packed_git *p,
1194                                      off_t obj_offset,
1195                                      unsigned long *size,
1196                                      unsigned long *store_size,
1197                                      unsigned int *delta_chain_length,
1198                                      unsigned char *base_sha1)
1199{
1200        struct pack_window *w_curs = NULL;
1201        off_t curpos;
1202        unsigned long dummy;
1203        unsigned char *next_sha1;
1204        enum object_type type;
1205
1206        *delta_chain_length = 0;
1207        curpos = obj_offset;
1208        type = unpack_object_header(p, &w_curs, &curpos, size);
1209
1210        for (;;) {
1211                switch (type) {
1212                default:
1213                        die("pack %s contains unknown object type %d",
1214                            p->pack_name, type);
1215                case OBJ_COMMIT:
1216                case OBJ_TREE:
1217                case OBJ_BLOB:
1218                case OBJ_TAG:
1219                        *store_size = 0; /* notyet */
1220                        unuse_pack(&w_curs);
1221                        return typename(type);
1222                case OBJ_OFS_DELTA:
1223                        obj_offset = get_delta_base(p, &w_curs, &curpos, type, obj_offset);
1224                        if (*delta_chain_length == 0) {
1225                                /* TODO: find base_sha1 as pointed by curpos */
1226                                hashclr(base_sha1);
1227                        }
1228                        break;
1229                case OBJ_REF_DELTA:
1230                        next_sha1 = use_pack(p, &w_curs, curpos, NULL);
1231                        if (*delta_chain_length == 0)
1232                                hashcpy(base_sha1, next_sha1);
1233                        obj_offset = find_pack_entry_one(next_sha1, p);
1234                        break;
1235                }
1236                (*delta_chain_length)++;
1237                curpos = obj_offset;
1238                type = unpack_object_header(p, &w_curs, &curpos, &dummy);
1239        }
1240}
1241
1242static int packed_object_info(struct packed_git *p, off_t obj_offset,
1243                              unsigned long *sizep)
1244{
1245        struct pack_window *w_curs = NULL;
1246        unsigned long size;
1247        off_t curpos = obj_offset;
1248        enum object_type type;
1249
1250        type = unpack_object_header(p, &w_curs, &curpos, &size);
1251
1252        switch (type) {
1253        case OBJ_OFS_DELTA:
1254        case OBJ_REF_DELTA:
1255                type = packed_delta_info(p, &w_curs, curpos,
1256                                         type, obj_offset, sizep);
1257                break;
1258        case OBJ_COMMIT:
1259        case OBJ_TREE:
1260        case OBJ_BLOB:
1261        case OBJ_TAG:
1262                if (sizep)
1263                        *sizep = size;
1264                break;
1265        default:
1266                die("pack %s contains unknown object type %d",
1267                    p->pack_name, type);
1268        }
1269        unuse_pack(&w_curs);
1270        return type;
1271}
1272
1273static void *unpack_compressed_entry(struct packed_git *p,
1274                                    struct pack_window **w_curs,
1275                                    off_t curpos,
1276                                    unsigned long size)
1277{
1278        int st;
1279        z_stream stream;
1280        unsigned char *buffer, *in;
1281
1282        buffer = xmalloc(size + 1);
1283        buffer[size] = 0;
1284        memset(&stream, 0, sizeof(stream));
1285        stream.next_out = buffer;
1286        stream.avail_out = size;
1287
1288        inflateInit(&stream);
1289        do {
1290                in = use_pack(p, w_curs, curpos, &stream.avail_in);
1291                stream.next_in = in;
1292                st = inflate(&stream, Z_FINISH);
1293                curpos += stream.next_in - in;
1294        } while (st == Z_OK || st == Z_BUF_ERROR);
1295        inflateEnd(&stream);
1296        if ((st != Z_STREAM_END) || stream.total_out != size) {
1297                free(buffer);
1298                return NULL;
1299        }
1300
1301        return buffer;
1302}
1303
1304static void *unpack_delta_entry(struct packed_git *p,
1305                                struct pack_window **w_curs,
1306                                off_t curpos,
1307                                unsigned long delta_size,
1308                                off_t obj_offset,
1309                                enum object_type *type,
1310                                unsigned long *sizep)
1311{
1312        void *delta_data, *result, *base;
1313        unsigned long base_size;
1314        off_t base_offset;
1315
1316        base_offset = get_delta_base(p, w_curs, &curpos, *type, obj_offset);
1317        base = unpack_entry(p, base_offset, type, &base_size);
1318        if (!base)
1319                die("failed to read delta base object"
1320                    " at %"PRIuMAX" from %s",
1321                    (uintmax_t)base_offset, p->pack_name);
1322
1323        delta_data = unpack_compressed_entry(p, w_curs, curpos, delta_size);
1324        result = patch_delta(base, base_size,
1325                             delta_data, delta_size,
1326                             sizep);
1327        if (!result)
1328                die("failed to apply delta");
1329        free(delta_data);
1330        free(base);
1331        return result;
1332}
1333
1334void *unpack_entry(struct packed_git *p, off_t obj_offset,
1335                   enum object_type *type, unsigned long *sizep)
1336{
1337        struct pack_window *w_curs = NULL;
1338        off_t curpos = obj_offset;
1339        void *data;
1340
1341        *type = unpack_object_header(p, &w_curs, &curpos, sizep);
1342        switch (*type) {
1343        case OBJ_OFS_DELTA:
1344        case OBJ_REF_DELTA:
1345                data = unpack_delta_entry(p, &w_curs, curpos, *sizep,
1346                                          obj_offset, type, sizep);
1347                break;
1348        case OBJ_COMMIT:
1349        case OBJ_TREE:
1350        case OBJ_BLOB:
1351        case OBJ_TAG:
1352                data = unpack_compressed_entry(p, &w_curs, curpos, *sizep);
1353                break;
1354        default:
1355                die("unknown object type %i in %s", *type, p->pack_name);
1356        }
1357        unuse_pack(&w_curs);
1358        return data;
1359}
1360
1361uint32_t num_packed_objects(const struct packed_git *p)
1362{
1363        /* See check_packed_git_idx() */
1364        return (uint32_t)((p->index_size - 20 - 20 - 4*256) / 24);
1365}
1366
1367int nth_packed_object_sha1(const struct packed_git *p, uint32_t n,
1368                           unsigned char* sha1)
1369{
1370        void *index = p->index_base + 256;
1371        if (num_packed_objects(p) <= n)
1372                return -1;
1373        hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1374        return 0;
1375}
1376
1377off_t find_pack_entry_one(const unsigned char *sha1,
1378                                  struct packed_git *p)
1379{
1380        uint32_t *level1_ofs = p->index_base;
1381        int hi = ntohl(level1_ofs[*sha1]);
1382        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1383        void *index = p->index_base + 256;
1384
1385        do {
1386                int mi = (lo + hi) / 2;
1387                int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1388                if (!cmp)
1389                        return ntohl(*((uint32_t *)((char *)index + (24 * mi))));
1390                if (cmp > 0)
1391                        hi = mi;
1392                else
1393                        lo = mi+1;
1394        } while (lo < hi);
1395        return 0;
1396}
1397
1398static int matches_pack_name(struct packed_git *p, const char *ig)
1399{
1400        const char *last_c, *c;
1401
1402        if (!strcmp(p->pack_name, ig))
1403                return 0;
1404
1405        for (c = p->pack_name, last_c = c; *c;)
1406                if (*c == '/')
1407                        last_c = ++c;
1408                else
1409                        ++c;
1410        if (!strcmp(last_c, ig))
1411                return 0;
1412
1413        return 1;
1414}
1415
1416static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1417{
1418        struct packed_git *p;
1419        off_t offset;
1420
1421        prepare_packed_git();
1422
1423        for (p = packed_git; p; p = p->next) {
1424                if (ignore_packed) {
1425                        const char **ig;
1426                        for (ig = ignore_packed; *ig; ig++)
1427                                if (!matches_pack_name(p, *ig))
1428                                        break;
1429                        if (*ig)
1430                                continue;
1431                }
1432                offset = find_pack_entry_one(sha1, p);
1433                if (offset) {
1434                        /*
1435                         * We are about to tell the caller where they can
1436                         * locate the requested object.  We better make
1437                         * sure the packfile is still here and can be
1438                         * accessed before supplying that answer, as
1439                         * it may have been deleted since the index
1440                         * was loaded!
1441                         */
1442                        if (p->pack_fd == -1 && open_packed_git(p)) {
1443                                error("packfile %s cannot be accessed", p->pack_name);
1444                                continue;
1445                        }
1446                        e->offset = offset;
1447                        e->p = p;
1448                        hashcpy(e->sha1, sha1);
1449                        return 1;
1450                }
1451        }
1452        return 0;
1453}
1454
1455struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1456                                  struct packed_git *packs)
1457{
1458        struct packed_git *p;
1459
1460        for (p = packs; p; p = p->next) {
1461                if (find_pack_entry_one(sha1, p))
1462                        return p;
1463        }
1464        return NULL;
1465
1466}
1467
1468static int sha1_loose_object_info(const unsigned char *sha1, unsigned long *sizep)
1469{
1470        int status;
1471        unsigned long mapsize, size;
1472        void *map;
1473        z_stream stream;
1474        char hdr[32];
1475
1476        map = map_sha1_file(sha1, &mapsize);
1477        if (!map)
1478                return error("unable to find %s", sha1_to_hex(sha1));
1479        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1480                status = error("unable to unpack %s header",
1481                               sha1_to_hex(sha1));
1482        else if ((status = parse_sha1_header(hdr, &size)) < 0)
1483                status = error("unable to parse %s header", sha1_to_hex(sha1));
1484        else if (sizep)
1485                *sizep = size;
1486        inflateEnd(&stream);
1487        munmap(map, mapsize);
1488        return status;
1489}
1490
1491int sha1_object_info(const unsigned char *sha1, unsigned long *sizep)
1492{
1493        struct pack_entry e;
1494
1495        if (!find_pack_entry(sha1, &e, NULL)) {
1496                reprepare_packed_git();
1497                if (!find_pack_entry(sha1, &e, NULL))
1498                        return sha1_loose_object_info(sha1, sizep);
1499        }
1500        return packed_object_info(e.p, e.offset, sizep);
1501}
1502
1503static void *read_packed_sha1(const unsigned char *sha1,
1504                              enum object_type *type, unsigned long *size)
1505{
1506        struct pack_entry e;
1507
1508        if (!find_pack_entry(sha1, &e, NULL))
1509                return NULL;
1510        else
1511                return unpack_entry(e.p, e.offset, type, size);
1512}
1513
1514/*
1515 * This is meant to hold a *small* number of objects that you would
1516 * want read_sha1_file() to be able to return, but yet you do not want
1517 * to write them into the object store (e.g. a browse-only
1518 * application).
1519 */
1520static struct cached_object {
1521        unsigned char sha1[20];
1522        enum object_type type;
1523        void *buf;
1524        unsigned long size;
1525} *cached_objects;
1526static int cached_object_nr, cached_object_alloc;
1527
1528static struct cached_object *find_cached_object(const unsigned char *sha1)
1529{
1530        int i;
1531        struct cached_object *co = cached_objects;
1532
1533        for (i = 0; i < cached_object_nr; i++, co++) {
1534                if (!hashcmp(co->sha1, sha1))
1535                        return co;
1536        }
1537        return NULL;
1538}
1539
1540int pretend_sha1_file(void *buf, unsigned long len, enum object_type type,
1541                      unsigned char *sha1)
1542{
1543        struct cached_object *co;
1544
1545        hash_sha1_file(buf, len, typename(type), sha1);
1546        if (has_sha1_file(sha1) || find_cached_object(sha1))
1547                return 0;
1548        if (cached_object_alloc <= cached_object_nr) {
1549                cached_object_alloc = alloc_nr(cached_object_alloc);
1550                cached_objects = xrealloc(cached_objects,
1551                                          sizeof(*cached_objects) *
1552                                          cached_object_alloc);
1553        }
1554        co = &cached_objects[cached_object_nr++];
1555        co->size = len;
1556        co->type = type;
1557        co->buf = xmalloc(len);
1558        memcpy(co->buf, buf, len);
1559        hashcpy(co->sha1, sha1);
1560        return 0;
1561}
1562
1563void *read_sha1_file(const unsigned char *sha1, enum object_type *type,
1564                     unsigned long *size)
1565{
1566        unsigned long mapsize;
1567        void *map, *buf;
1568        struct cached_object *co;
1569
1570        co = find_cached_object(sha1);
1571        if (co) {
1572                buf = xmalloc(co->size + 1);
1573                memcpy(buf, co->buf, co->size);
1574                ((char*)buf)[co->size] = 0;
1575                *type = co->type;
1576                *size = co->size;
1577                return buf;
1578        }
1579
1580        buf = read_packed_sha1(sha1, type, size);
1581        if (buf)
1582                return buf;
1583        map = map_sha1_file(sha1, &mapsize);
1584        if (map) {
1585                buf = unpack_sha1_file(map, mapsize, type, size, sha1);
1586                munmap(map, mapsize);
1587                return buf;
1588        }
1589        reprepare_packed_git();
1590        return read_packed_sha1(sha1, type, size);
1591}
1592
1593void *read_object_with_reference(const unsigned char *sha1,
1594                                 const char *required_type_name,
1595                                 unsigned long *size,
1596                                 unsigned char *actual_sha1_return)
1597{
1598        enum object_type type, required_type;
1599        void *buffer;
1600        unsigned long isize;
1601        unsigned char actual_sha1[20];
1602
1603        required_type = type_from_string(required_type_name);
1604        hashcpy(actual_sha1, sha1);
1605        while (1) {
1606                int ref_length = -1;
1607                const char *ref_type = NULL;
1608
1609                buffer = read_sha1_file(actual_sha1, &type, &isize);
1610                if (!buffer)
1611                        return NULL;
1612                if (type == required_type) {
1613                        *size = isize;
1614                        if (actual_sha1_return)
1615                                hashcpy(actual_sha1_return, actual_sha1);
1616                        return buffer;
1617                }
1618                /* Handle references */
1619                else if (type == OBJ_COMMIT)
1620                        ref_type = "tree ";
1621                else if (type == OBJ_TAG)
1622                        ref_type = "object ";
1623                else {
1624                        free(buffer);
1625                        return NULL;
1626                }
1627                ref_length = strlen(ref_type);
1628
1629                if (memcmp(buffer, ref_type, ref_length) ||
1630                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1631                        free(buffer);
1632                        return NULL;
1633                }
1634                free(buffer);
1635                /* Now we have the ID of the referred-to object in
1636                 * actual_sha1.  Check again. */
1637        }
1638}
1639
1640static void write_sha1_file_prepare(void *buf, unsigned long len,
1641                                    const char *type, unsigned char *sha1,
1642                                    char *hdr, int *hdrlen)
1643{
1644        SHA_CTX c;
1645
1646        /* Generate the header */
1647        *hdrlen = sprintf(hdr, "%s %lu", type, len)+1;
1648
1649        /* Sha1.. */
1650        SHA1_Init(&c);
1651        SHA1_Update(&c, hdr, *hdrlen);
1652        SHA1_Update(&c, buf, len);
1653        SHA1_Final(sha1, &c);
1654}
1655
1656/*
1657 * Link the tempfile to the final place, possibly creating the
1658 * last directory level as you do so.
1659 *
1660 * Returns the errno on failure, 0 on success.
1661 */
1662static int link_temp_to_file(const char *tmpfile, const char *filename)
1663{
1664        int ret;
1665        char *dir;
1666
1667        if (!link(tmpfile, filename))
1668                return 0;
1669
1670        /*
1671         * Try to mkdir the last path component if that failed.
1672         *
1673         * Re-try the "link()" regardless of whether the mkdir
1674         * succeeds, since a race might mean that somebody
1675         * else succeeded.
1676         */
1677        ret = errno;
1678        dir = strrchr(filename, '/');
1679        if (dir) {
1680                *dir = 0;
1681                if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1682                        *dir = '/';
1683                        return -2;
1684                }
1685                *dir = '/';
1686                if (!link(tmpfile, filename))
1687                        return 0;
1688                ret = errno;
1689        }
1690        return ret;
1691}
1692
1693/*
1694 * Move the just written object into its final resting place
1695 */
1696int move_temp_to_file(const char *tmpfile, const char *filename)
1697{
1698        int ret = link_temp_to_file(tmpfile, filename);
1699
1700        /*
1701         * Coda hack - coda doesn't like cross-directory links,
1702         * so we fall back to a rename, which will mean that it
1703         * won't be able to check collisions, but that's not a
1704         * big deal.
1705         *
1706         * The same holds for FAT formatted media.
1707         *
1708         * When this succeeds, we just return 0. We have nothing
1709         * left to unlink.
1710         */
1711        if (ret && ret != EEXIST) {
1712                if (!rename(tmpfile, filename))
1713                        return 0;
1714                ret = errno;
1715        }
1716        unlink(tmpfile);
1717        if (ret) {
1718                if (ret != EEXIST) {
1719                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1720                }
1721                /* FIXME!!! Collision check here ? */
1722        }
1723
1724        return 0;
1725}
1726
1727static int write_buffer(int fd, const void *buf, size_t len)
1728{
1729        if (write_in_full(fd, buf, len) < 0)
1730                return error("file write error (%s)", strerror(errno));
1731        return 0;
1732}
1733
1734static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1735{
1736        int hdr_len;
1737        unsigned char c;
1738
1739        c = (type << 4) | (len & 15);
1740        len >>= 4;
1741        hdr_len = 1;
1742        while (len) {
1743                *hdr++ = c | 0x80;
1744                hdr_len++;
1745                c = (len & 0x7f);
1746                len >>= 7;
1747        }
1748        *hdr = c;
1749        return hdr_len;
1750}
1751
1752static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1753{
1754        int obj_type, hdrlen;
1755
1756        if (use_legacy_headers) {
1757                while (deflate(stream, 0) == Z_OK)
1758                        /* nothing */;
1759                return;
1760        }
1761        obj_type = type_from_string(type);
1762        hdrlen = write_binary_header(stream->next_out, obj_type, len);
1763        stream->total_out = hdrlen;
1764        stream->next_out += hdrlen;
1765        stream->avail_out -= hdrlen;
1766}
1767
1768int hash_sha1_file(void *buf, unsigned long len, const char *type,
1769                   unsigned char *sha1)
1770{
1771        char hdr[32];
1772        int hdrlen;
1773        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1774        return 0;
1775}
1776
1777int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1778{
1779        int size;
1780        unsigned char *compressed;
1781        z_stream stream;
1782        unsigned char sha1[20];
1783        char *filename;
1784        static char tmpfile[PATH_MAX];
1785        char hdr[32];
1786        int fd, hdrlen;
1787
1788        /* Normally if we have it in the pack then we do not bother writing
1789         * it out into .git/objects/??/?{38} file.
1790         */
1791        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1792        filename = sha1_file_name(sha1);
1793        if (returnsha1)
1794                hashcpy(returnsha1, sha1);
1795        if (has_sha1_file(sha1))
1796                return 0;
1797        fd = open(filename, O_RDONLY);
1798        if (fd >= 0) {
1799                /*
1800                 * FIXME!!! We might do collision checking here, but we'd
1801                 * need to uncompress the old file and check it. Later.
1802                 */
1803                close(fd);
1804                return 0;
1805        }
1806
1807        if (errno != ENOENT) {
1808                return error("sha1 file %s: %s\n", filename, strerror(errno));
1809        }
1810
1811        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1812
1813        fd = mkstemp(tmpfile);
1814        if (fd < 0) {
1815                if (errno == EPERM)
1816                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1817                else
1818                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1819        }
1820
1821        /* Set it up */
1822        memset(&stream, 0, sizeof(stream));
1823        deflateInit(&stream, zlib_compression_level);
1824        size = 8 + deflateBound(&stream, len+hdrlen);
1825        compressed = xmalloc(size);
1826
1827        /* Compress it */
1828        stream.next_out = compressed;
1829        stream.avail_out = size;
1830
1831        /* First header.. */
1832        stream.next_in = (unsigned char *)hdr;
1833        stream.avail_in = hdrlen;
1834        setup_object_header(&stream, type, len);
1835
1836        /* Then the data itself.. */
1837        stream.next_in = buf;
1838        stream.avail_in = len;
1839        while (deflate(&stream, Z_FINISH) == Z_OK)
1840                /* nothing */;
1841        deflateEnd(&stream);
1842        size = stream.total_out;
1843
1844        if (write_buffer(fd, compressed, size) < 0)
1845                die("unable to write sha1 file");
1846        fchmod(fd, 0444);
1847        close(fd);
1848        free(compressed);
1849
1850        return move_temp_to_file(tmpfile, filename);
1851}
1852
1853/*
1854 * We need to unpack and recompress the object for writing
1855 * it out to a different file.
1856 */
1857static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1858{
1859        size_t size;
1860        z_stream stream;
1861        unsigned char *unpacked;
1862        unsigned long len;
1863        enum object_type type;
1864        char hdr[32];
1865        int hdrlen;
1866        void *buf;
1867
1868        /* need to unpack and recompress it by itself */
1869        unpacked = read_packed_sha1(sha1, &type, &len);
1870        if (!unpacked)
1871                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1872
1873        hdrlen = sprintf(hdr, "%s %lu", typename(type), len) + 1;
1874
1875        /* Set it up */
1876        memset(&stream, 0, sizeof(stream));
1877        deflateInit(&stream, zlib_compression_level);
1878        size = deflateBound(&stream, len + hdrlen);
1879        buf = xmalloc(size);
1880
1881        /* Compress it */
1882        stream.next_out = buf;
1883        stream.avail_out = size;
1884
1885        /* First header.. */
1886        stream.next_in = (void *)hdr;
1887        stream.avail_in = hdrlen;
1888        while (deflate(&stream, 0) == Z_OK)
1889                /* nothing */;
1890
1891        /* Then the data itself.. */
1892        stream.next_in = unpacked;
1893        stream.avail_in = len;
1894        while (deflate(&stream, Z_FINISH) == Z_OK)
1895                /* nothing */;
1896        deflateEnd(&stream);
1897        free(unpacked);
1898
1899        *objsize = stream.total_out;
1900        return buf;
1901}
1902
1903int write_sha1_to_fd(int fd, const unsigned char *sha1)
1904{
1905        int retval;
1906        unsigned long objsize;
1907        void *buf = map_sha1_file(sha1, &objsize);
1908
1909        if (buf) {
1910                retval = write_buffer(fd, buf, objsize);
1911                munmap(buf, objsize);
1912                return retval;
1913        }
1914
1915        buf = repack_object(sha1, &objsize);
1916        retval = write_buffer(fd, buf, objsize);
1917        free(buf);
1918        return retval;
1919}
1920
1921int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1922                       size_t bufsize, size_t *bufposn)
1923{
1924        char tmpfile[PATH_MAX];
1925        int local;
1926        z_stream stream;
1927        unsigned char real_sha1[20];
1928        unsigned char discard[4096];
1929        int ret;
1930        SHA_CTX c;
1931
1932        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1933
1934        local = mkstemp(tmpfile);
1935        if (local < 0) {
1936                if (errno == EPERM)
1937                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1938                else
1939                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1940        }
1941
1942        memset(&stream, 0, sizeof(stream));
1943
1944        inflateInit(&stream);
1945
1946        SHA1_Init(&c);
1947
1948        do {
1949                ssize_t size;
1950                if (*bufposn) {
1951                        stream.avail_in = *bufposn;
1952                        stream.next_in = (unsigned char *) buffer;
1953                        do {
1954                                stream.next_out = discard;
1955                                stream.avail_out = sizeof(discard);
1956                                ret = inflate(&stream, Z_SYNC_FLUSH);
1957                                SHA1_Update(&c, discard, sizeof(discard) -
1958                                            stream.avail_out);
1959                        } while (stream.avail_in && ret == Z_OK);
1960                        if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1961                                die("unable to write sha1 file");
1962                        memmove(buffer, buffer + *bufposn - stream.avail_in,
1963                                stream.avail_in);
1964                        *bufposn = stream.avail_in;
1965                        if (ret != Z_OK)
1966                                break;
1967                }
1968                size = xread(fd, buffer + *bufposn, bufsize - *bufposn);
1969                if (size <= 0) {
1970                        close(local);
1971                        unlink(tmpfile);
1972                        if (!size)
1973                                return error("Connection closed?");
1974                        perror("Reading from connection");
1975                        return -1;
1976                }
1977                *bufposn += size;
1978        } while (1);
1979        inflateEnd(&stream);
1980
1981        close(local);
1982        SHA1_Final(real_sha1, &c);
1983        if (ret != Z_STREAM_END) {
1984                unlink(tmpfile);
1985                return error("File %s corrupted", sha1_to_hex(sha1));
1986        }
1987        if (hashcmp(sha1, real_sha1)) {
1988                unlink(tmpfile);
1989                return error("File %s has bad hash", sha1_to_hex(sha1));
1990        }
1991
1992        return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1993}
1994
1995int has_pack_index(const unsigned char *sha1)
1996{
1997        struct stat st;
1998        if (stat(sha1_pack_index_name(sha1), &st))
1999                return 0;
2000        return 1;
2001}
2002
2003int has_pack_file(const unsigned char *sha1)
2004{
2005        struct stat st;
2006        if (stat(sha1_pack_name(sha1), &st))
2007                return 0;
2008        return 1;
2009}
2010
2011int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
2012{
2013        struct pack_entry e;
2014        return find_pack_entry(sha1, &e, ignore_packed);
2015}
2016
2017int has_sha1_file(const unsigned char *sha1)
2018{
2019        struct stat st;
2020        struct pack_entry e;
2021
2022        if (find_pack_entry(sha1, &e, NULL))
2023                return 1;
2024        return find_sha1_file(sha1, &st) ? 1 : 0;
2025}
2026
2027/*
2028 * reads from fd as long as possible into a supplied buffer of size bytes.
2029 * If necessary the buffer's size is increased using realloc()
2030 *
2031 * returns 0 if anything went fine and -1 otherwise
2032 *
2033 * NOTE: both buf and size may change, but even when -1 is returned
2034 * you still have to free() it yourself.
2035 */
2036int read_pipe(int fd, char** return_buf, unsigned long* return_size)
2037{
2038        char* buf = *return_buf;
2039        unsigned long size = *return_size;
2040        int iret;
2041        unsigned long off = 0;
2042
2043        do {
2044                iret = xread(fd, buf + off, size - off);
2045                if (iret > 0) {
2046                        off += iret;
2047                        if (off == size) {
2048                                size *= 2;
2049                                buf = xrealloc(buf, size);
2050                        }
2051                }
2052        } while (iret > 0);
2053
2054        *return_buf = buf;
2055        *return_size = off;
2056
2057        if (iret < 0)
2058                return -1;
2059        return 0;
2060}
2061
2062int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
2063{
2064        unsigned long size = 4096;
2065        char *buf = xmalloc(size);
2066        int ret;
2067
2068        if (read_pipe(fd, &buf, &size)) {
2069                free(buf);
2070                return -1;
2071        }
2072
2073        if (!type)
2074                type = blob_type;
2075        if (write_object)
2076                ret = write_sha1_file(buf, size, type, sha1);
2077        else
2078                ret = hash_sha1_file(buf, size, type, sha1);
2079        free(buf);
2080        return ret;
2081}
2082
2083int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
2084             enum object_type type, const char *path)
2085{
2086        size_t size = xsize_t(st->st_size);
2087        void *buf = NULL;
2088        int ret, re_allocated = 0;
2089
2090        if (size)
2091                buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
2092        close(fd);
2093
2094        if (!type)
2095                type = OBJ_BLOB;
2096
2097        /*
2098         * Convert blobs to git internal format
2099         */
2100        if ((type == OBJ_BLOB) && S_ISREG(st->st_mode)) {
2101                unsigned long nsize = size;
2102                char *nbuf = buf;
2103                if (convert_to_git(path, &nbuf, &nsize)) {
2104                        if (size)
2105                                munmap(buf, size);
2106                        size = nsize;
2107                        buf = nbuf;
2108                        re_allocated = 1;
2109                }
2110        }
2111
2112        if (write_object)
2113                ret = write_sha1_file(buf, size, typename(type), sha1);
2114        else
2115                ret = hash_sha1_file(buf, size, typename(type), sha1);
2116        if (re_allocated) {
2117                free(buf);
2118                return ret;
2119        }
2120        if (size)
2121                munmap(buf, size);
2122        return ret;
2123}
2124
2125int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
2126{
2127        int fd;
2128        char *target;
2129        size_t len;
2130
2131        switch (st->st_mode & S_IFMT) {
2132        case S_IFREG:
2133                fd = open(path, O_RDONLY);
2134                if (fd < 0)
2135                        return error("open(\"%s\"): %s", path,
2136                                     strerror(errno));
2137                if (index_fd(sha1, fd, st, write_object, OBJ_BLOB, path) < 0)
2138                        return error("%s: failed to insert into database",
2139                                     path);
2140                break;
2141        case S_IFLNK:
2142                len = xsize_t(st->st_size);
2143                target = xmalloc(len + 1);
2144                if (readlink(path, target, len + 1) != st->st_size) {
2145                        char *errstr = strerror(errno);
2146                        free(target);
2147                        return error("readlink(\"%s\"): %s", path,
2148                                     errstr);
2149                }
2150                if (!write_object)
2151                        hash_sha1_file(target, len, blob_type, sha1);
2152                else if (write_sha1_file(target, len, blob_type, sha1))
2153                        return error("%s: failed to insert into database",
2154                                     path);
2155                free(target);
2156                break;
2157        default:
2158                return error("%s: unsupported file type", path);
2159        }
2160        return 0;
2161}
2162
2163int read_pack_header(int fd, struct pack_header *header)
2164{
2165        char *c = (char*)header;
2166        ssize_t remaining = sizeof(struct pack_header);
2167        do {
2168                ssize_t r = xread(fd, c, remaining);
2169                if (r <= 0)
2170                        /* "eof before pack header was fully read" */
2171                        return PH_ERROR_EOF;
2172                remaining -= r;
2173                c += r;
2174        } while (remaining > 0);
2175        if (header->hdr_signature != htonl(PACK_SIGNATURE))
2176                /* "protocol error (pack signature mismatch detected)" */
2177                return PH_ERROR_PACK_SIGNATURE;
2178        if (!pack_version_ok(header->hdr_version))
2179                /* "protocol error (pack version unsupported)" */
2180                return PH_ERROR_PROTOCOL;
2181        return 0;
2182}