8e14a5a882c8ff7893b1d548390f7359f60d8fa4
   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
  25const unsigned char null_sha1[20];
  26
  27static unsigned int sha1_file_open_flag = O_NOATIME;
  28
  29signed 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
  64int 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
  77int 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
 110char * 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
 128static 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 */
 150char *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
 168char *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
 193char *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
 218struct alternate_object_database *alt_odb_list;
 219static struct alternate_object_database **alt_odb_tail;
 220
 221static 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 */
 238static 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
 306static 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
 343static void read_info_alternates(const char * relative_base, int depth)
 344{
 345        char *map;
 346        struct stat st;
 347        char path[PATH_MAX];
 348        int fd;
 349
 350        sprintf(path, "%s/info/alternates", relative_base);
 351        fd = open(path, O_RDONLY);
 352        if (fd < 0)
 353                return;
 354        if (fstat(fd, &st) || (st.st_size == 0)) {
 355                close(fd);
 356                return;
 357        }
 358        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 359        close(fd);
 360        if (map == MAP_FAILED)
 361                return;
 362
 363        link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
 364
 365        munmap(map, st.st_size);
 366}
 367
 368void prepare_alt_odb(void)
 369{
 370        const char *alt;
 371
 372        alt = getenv(ALTERNATE_DB_ENVIRONMENT);
 373        if (!alt) alt = "";
 374
 375        if (alt_odb_tail)
 376                return;
 377        alt_odb_tail = &alt_odb_list;
 378        link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
 379
 380        read_info_alternates(get_object_directory(), 0);
 381}
 382
 383static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
 384{
 385        char *name = sha1_file_name(sha1);
 386        struct alternate_object_database *alt;
 387
 388        if (!stat(name, st))
 389                return name;
 390        prepare_alt_odb();
 391        for (alt = alt_odb_list; alt; alt = alt->next) {
 392                name = alt->name;
 393                fill_sha1_path(name, sha1);
 394                if (!stat(alt->base, st))
 395                        return alt->base;
 396        }
 397        return NULL;
 398}
 399
 400static int pack_used_ctr;
 401static unsigned long pack_mapped;
 402struct packed_git *packed_git;
 403
 404static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
 405                                void **idx_map_)
 406{
 407        void *idx_map;
 408        unsigned int *index;
 409        unsigned long idx_size;
 410        int nr, i;
 411        int fd = open(path, O_RDONLY);
 412        struct stat st;
 413        if (fd < 0)
 414                return -1;
 415        if (fstat(fd, &st)) {
 416                close(fd);
 417                return -1;
 418        }
 419        idx_size = st.st_size;
 420        idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
 421        close(fd);
 422        if (idx_map == MAP_FAILED)
 423                return -1;
 424
 425        index = idx_map;
 426        *idx_map_ = idx_map;
 427        *idx_size_ = idx_size;
 428
 429        /* check index map */
 430        if (idx_size < 4*256 + 20 + 20)
 431                return error("index file too small");
 432        nr = 0;
 433        for (i = 0; i < 256; i++) {
 434                unsigned int n = ntohl(index[i]);
 435                if (n < nr)
 436                        return error("non-monotonic index");
 437                nr = n;
 438        }
 439
 440        /*
 441         * Total size:
 442         *  - 256 index entries 4 bytes each
 443         *  - 24-byte entries * nr (20-byte sha1 + 4-byte offset)
 444         *  - 20-byte SHA1 of the packfile
 445         *  - 20-byte SHA1 file checksum
 446         */
 447        if (idx_size != 4*256 + nr * 24 + 20 + 20)
 448                return error("wrong index file size");
 449
 450        return 0;
 451}
 452
 453static int unuse_one_window(void)
 454{
 455        struct packed_git *p, *lru_p = NULL;
 456        struct pack_window *w, *w_l, *lru_w = NULL, *lru_l = NULL;
 457
 458        for (p = packed_git; p; p = p->next) {
 459                for (w_l = NULL, w = p->windows; w; w = w->next) {
 460                        if (!w->inuse_cnt) {
 461                                if (!lru_w || w->last_used < lru_w->last_used) {
 462                                        lru_p = p;
 463                                        lru_w = w;
 464                                        lru_l = w_l;
 465                                }
 466                        }
 467                        w_l = w;
 468                }
 469        }
 470        if (lru_p) {
 471                munmap(lru_w->base, lru_w->len);
 472                pack_mapped -= lru_w->len;
 473                if (lru_l)
 474                        lru_l->next = lru_w->next;
 475                else {
 476                        lru_p->windows = lru_w->next;
 477                        if (!lru_p->windows) {
 478                                close(lru_p->pack_fd);
 479                                lru_p->pack_fd = -1;
 480                        }
 481                }
 482                free(lru_w);
 483                return 1;
 484        }
 485        return 0;
 486}
 487
 488void unuse_pack(struct pack_window **w_cursor)
 489{
 490        struct pack_window *w = *w_cursor;
 491        if (w) {
 492                w->inuse_cnt--;
 493                *w_cursor = NULL;
 494        }
 495}
 496
 497static void open_packed_git(struct packed_git *p)
 498{
 499        struct stat st;
 500        struct pack_header hdr;
 501        unsigned char sha1[20];
 502        unsigned char *idx_sha1;
 503
 504        p->pack_fd = open(p->pack_name, O_RDONLY);
 505        if (p->pack_fd < 0 || fstat(p->pack_fd, &st))
 506                die("packfile %s cannot be opened", p->pack_name);
 507
 508        /* If we created the struct before we had the pack we lack size. */
 509        if (!p->pack_size) {
 510                if (!S_ISREG(st.st_mode))
 511                        die("packfile %s not a regular file", p->pack_name);
 512                p->pack_size = st.st_size;
 513        } else if (p->pack_size != st.st_size)
 514                die("packfile %s size changed", p->pack_name);
 515
 516        /* Verify we recognize this pack file format. */
 517        read_or_die(p->pack_fd, &hdr, sizeof(hdr));
 518        if (hdr.hdr_signature != htonl(PACK_SIGNATURE))
 519                die("file %s is not a GIT packfile", p->pack_name);
 520        if (!pack_version_ok(hdr.hdr_version))
 521                die("packfile %s is version %u and not supported"
 522                        " (try upgrading GIT to a newer version)",
 523                        p->pack_name, ntohl(hdr.hdr_version));
 524
 525        /* Verify the pack matches its index. */
 526        if (num_packed_objects(p) != ntohl(hdr.hdr_entries))
 527                die("packfile %s claims to have %u objects"
 528                        " while index size indicates %u objects",
 529                        p->pack_name, ntohl(hdr.hdr_entries),
 530                        num_packed_objects(p));
 531        if (lseek(p->pack_fd, p->pack_size - sizeof(sha1), SEEK_SET) == -1)
 532                die("end of packfile %s is unavailable", p->pack_name);
 533        read_or_die(p->pack_fd, sha1, sizeof(sha1));
 534        idx_sha1 = ((unsigned char *)p->index_base) + p->index_size - 40;
 535        if (hashcmp(sha1, idx_sha1))
 536                die("packfile %s does not match index", p->pack_name);
 537}
 538
 539unsigned char* use_pack(struct packed_git *p,
 540                struct pack_window **w_cursor,
 541                unsigned long offset,
 542                unsigned int *left)
 543{
 544        struct pack_window *win = p->windows;
 545
 546        if (p->pack_fd == -1)
 547                open_packed_git(p);
 548        if (!win) {
 549                pack_mapped += p->pack_size;
 550                while (packed_git_limit < pack_mapped && unuse_one_window())
 551                        ; /* nothing */
 552                win = xcalloc(1, sizeof(*win));
 553                win->len = p->pack_size;
 554                win->base = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, p->pack_fd, 0);
 555                if (win->base == MAP_FAILED)
 556                        die("packfile %s cannot be mapped.", p->pack_name);
 557                p->windows = win;
 558        }
 559        if (win != *w_cursor) {
 560                win->last_used = pack_used_ctr++;
 561                win->inuse_cnt++;
 562                *w_cursor = win;
 563        }
 564        if (left)
 565                *left = win->len - offset;
 566        return win->base + offset;
 567}
 568
 569struct packed_git *add_packed_git(char *path, int path_len, int local)
 570{
 571        struct stat st;
 572        struct packed_git *p;
 573        unsigned long idx_size;
 574        void *idx_map;
 575        unsigned char sha1[20];
 576
 577        if (check_packed_git_idx(path, &idx_size, &idx_map))
 578                return NULL;
 579
 580        /* do we have a corresponding .pack file? */
 581        strcpy(path + path_len - 4, ".pack");
 582        if (stat(path, &st) || !S_ISREG(st.st_mode)) {
 583                munmap(idx_map, idx_size);
 584                return NULL;
 585        }
 586        /* ok, it looks sane as far as we can check without
 587         * actually mapping the pack file.
 588         */
 589        p = xmalloc(sizeof(*p) + path_len + 2);
 590        strcpy(p->pack_name, path);
 591        p->index_size = idx_size;
 592        p->pack_size = st.st_size;
 593        p->index_base = idx_map;
 594        p->next = NULL;
 595        p->windows = NULL;
 596        p->pack_fd = -1;
 597        p->pack_local = local;
 598        if ((path_len > 44) && !get_sha1_hex(path + path_len - 44, sha1))
 599                hashcpy(p->sha1, sha1);
 600        return p;
 601}
 602
 603struct packed_git *parse_pack_index(unsigned char *sha1)
 604{
 605        char *path = sha1_pack_index_name(sha1);
 606        return parse_pack_index_file(sha1, path);
 607}
 608
 609struct packed_git *parse_pack_index_file(const unsigned char *sha1, char *idx_path)
 610{
 611        struct packed_git *p;
 612        unsigned long idx_size;
 613        void *idx_map;
 614        char *path;
 615
 616        if (check_packed_git_idx(idx_path, &idx_size, &idx_map))
 617                return NULL;
 618
 619        path = sha1_pack_name(sha1);
 620
 621        p = xmalloc(sizeof(*p) + strlen(path) + 2);
 622        strcpy(p->pack_name, path);
 623        p->index_size = idx_size;
 624        p->pack_size = 0;
 625        p->index_base = idx_map;
 626        p->next = NULL;
 627        p->windows = NULL;
 628        p->pack_fd = -1;
 629        hashcpy(p->sha1, sha1);
 630        return p;
 631}
 632
 633void install_packed_git(struct packed_git *pack)
 634{
 635        pack->next = packed_git;
 636        packed_git = pack;
 637}
 638
 639static void prepare_packed_git_one(char *objdir, int local)
 640{
 641        char path[PATH_MAX];
 642        int len;
 643        DIR *dir;
 644        struct dirent *de;
 645
 646        sprintf(path, "%s/pack", objdir);
 647        len = strlen(path);
 648        dir = opendir(path);
 649        if (!dir) {
 650                if (errno != ENOENT)
 651                        error("unable to open object pack directory: %s: %s",
 652                              path, strerror(errno));
 653                return;
 654        }
 655        path[len++] = '/';
 656        while ((de = readdir(dir)) != NULL) {
 657                int namelen = strlen(de->d_name);
 658                struct packed_git *p;
 659
 660                if (!has_extension(de->d_name, ".idx"))
 661                        continue;
 662
 663                /* we have .idx.  Is it a file we can map? */
 664                strcpy(path + len, de->d_name);
 665                for (p = packed_git; p; p = p->next) {
 666                        if (!memcmp(path, p->pack_name, len + namelen - 4))
 667                                break;
 668                }
 669                if (p)
 670                        continue;
 671                p = add_packed_git(path, len + namelen, local);
 672                if (!p)
 673                        continue;
 674                p->next = packed_git;
 675                packed_git = p;
 676        }
 677        closedir(dir);
 678}
 679
 680static int prepare_packed_git_run_once = 0;
 681void prepare_packed_git(void)
 682{
 683        struct alternate_object_database *alt;
 684
 685        if (prepare_packed_git_run_once)
 686                return;
 687        prepare_packed_git_one(get_object_directory(), 1);
 688        prepare_alt_odb();
 689        for (alt = alt_odb_list; alt; alt = alt->next) {
 690                alt->name[-1] = 0;
 691                prepare_packed_git_one(alt->base, 0);
 692                alt->name[-1] = '/';
 693        }
 694        prepare_packed_git_run_once = 1;
 695}
 696
 697void reprepare_packed_git(void)
 698{
 699        prepare_packed_git_run_once = 0;
 700        prepare_packed_git();
 701}
 702
 703int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
 704{
 705        unsigned char real_sha1[20];
 706        hash_sha1_file(map, size, type, real_sha1);
 707        return hashcmp(sha1, real_sha1) ? -1 : 0;
 708}
 709
 710void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
 711{
 712        struct stat st;
 713        void *map;
 714        int fd;
 715        char *filename = find_sha1_file(sha1, &st);
 716
 717        if (!filename) {
 718                return NULL;
 719        }
 720
 721        fd = open(filename, O_RDONLY | sha1_file_open_flag);
 722        if (fd < 0) {
 723                /* See if it works without O_NOATIME */
 724                switch (sha1_file_open_flag) {
 725                default:
 726                        fd = open(filename, O_RDONLY);
 727                        if (fd >= 0)
 728                                break;
 729                /* Fallthrough */
 730                case 0:
 731                        return NULL;
 732                }
 733
 734                /* If it failed once, it will probably fail again.
 735                 * Stop using O_NOATIME
 736                 */
 737                sha1_file_open_flag = 0;
 738        }
 739        map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
 740        close(fd);
 741        if (map == MAP_FAILED)
 742                return NULL;
 743        *size = st.st_size;
 744        return map;
 745}
 746
 747int legacy_loose_object(unsigned char *map)
 748{
 749        unsigned int word;
 750
 751        /*
 752         * Is it a zlib-compressed buffer? If so, the first byte
 753         * must be 0x78 (15-bit window size, deflated), and the
 754         * first 16-bit word is evenly divisible by 31
 755         */
 756        word = (map[0] << 8) + map[1];
 757        if (map[0] == 0x78 && !(word % 31))
 758                return 1;
 759        else
 760                return 0;
 761}
 762
 763unsigned long unpack_object_header_gently(const unsigned char *buf, unsigned long len, enum object_type *type, unsigned long *sizep)
 764{
 765        unsigned shift;
 766        unsigned char c;
 767        unsigned long size;
 768        unsigned long used = 0;
 769
 770        c = buf[used++];
 771        *type = (c >> 4) & 7;
 772        size = c & 15;
 773        shift = 4;
 774        while (c & 0x80) {
 775                if (len <= used)
 776                        return 0;
 777                if (sizeof(long) * 8 <= shift)
 778                        return 0;
 779                c = buf[used++];
 780                size += (c & 0x7f) << shift;
 781                shift += 7;
 782        }
 783        *sizep = size;
 784        return used;
 785}
 786
 787static int unpack_sha1_header(z_stream *stream, unsigned char *map, unsigned long mapsize, void *buffer, unsigned long bufsiz)
 788{
 789        unsigned long size, used;
 790        static const char valid_loose_object_type[8] = {
 791                0, /* OBJ_EXT */
 792                1, 1, 1, 1, /* "commit", "tree", "blob", "tag" */
 793                0, /* "delta" and others are invalid in a loose object */
 794        };
 795        enum object_type type;
 796
 797        /* Get the data stream */
 798        memset(stream, 0, sizeof(*stream));
 799        stream->next_in = map;
 800        stream->avail_in = mapsize;
 801        stream->next_out = buffer;
 802        stream->avail_out = bufsiz;
 803
 804        if (legacy_loose_object(map)) {
 805                inflateInit(stream);
 806                return inflate(stream, 0);
 807        }
 808
 809        used = unpack_object_header_gently(map, mapsize, &type, &size);
 810        if (!used || !valid_loose_object_type[type])
 811                return -1;
 812        map += used;
 813        mapsize -= used;
 814
 815        /* Set up the stream for the rest.. */
 816        stream->next_in = map;
 817        stream->avail_in = mapsize;
 818        inflateInit(stream);
 819
 820        /* And generate the fake traditional header */
 821        stream->total_out = 1 + snprintf(buffer, bufsiz, "%s %lu",
 822                                         type_names[type], size);
 823        return 0;
 824}
 825
 826static void *unpack_sha1_rest(z_stream *stream, void *buffer, unsigned long size)
 827{
 828        int bytes = strlen(buffer) + 1;
 829        unsigned char *buf = xmalloc(1+size);
 830        unsigned long n;
 831
 832        n = stream->total_out - bytes;
 833        if (n > size)
 834                n = size;
 835        memcpy(buf, (char *) buffer + bytes, n);
 836        bytes = n;
 837        if (bytes < size) {
 838                stream->next_out = buf + bytes;
 839                stream->avail_out = size - bytes;
 840                while (inflate(stream, Z_FINISH) == Z_OK)
 841                        /* nothing */;
 842        }
 843        buf[size] = 0;
 844        inflateEnd(stream);
 845        return buf;
 846}
 847
 848/*
 849 * We used to just use "sscanf()", but that's actually way
 850 * too permissive for what we want to check. So do an anal
 851 * object header parse by hand.
 852 */
 853static int parse_sha1_header(char *hdr, char *type, unsigned long *sizep)
 854{
 855        int i;
 856        unsigned long size;
 857
 858        /*
 859         * The type can be at most ten bytes (including the 
 860         * terminating '\0' that we add), and is followed by
 861         * a space. 
 862         */
 863        i = 10;
 864        for (;;) {
 865                char c = *hdr++;
 866                if (c == ' ')
 867                        break;
 868                if (!--i)
 869                        return -1;
 870                *type++ = c;
 871        }
 872        *type = 0;
 873
 874        /*
 875         * The length must follow immediately, and be in canonical
 876         * decimal format (ie "010" is not valid).
 877         */
 878        size = *hdr++ - '0';
 879        if (size > 9)
 880                return -1;
 881        if (size) {
 882                for (;;) {
 883                        unsigned long c = *hdr - '0';
 884                        if (c > 9)
 885                                break;
 886                        hdr++;
 887                        size = size * 10 + c;
 888                }
 889        }
 890        *sizep = size;
 891
 892        /*
 893         * The length must be followed by a zero byte
 894         */
 895        return *hdr ? -1 : 0;
 896}
 897
 898void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
 899{
 900        int ret;
 901        z_stream stream;
 902        char hdr[8192];
 903
 904        ret = unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr));
 905        if (ret < Z_OK || parse_sha1_header(hdr, type, size) < 0)
 906                return NULL;
 907
 908        return unpack_sha1_rest(&stream, hdr, *size);
 909}
 910
 911static unsigned long get_delta_base(struct packed_git *p,
 912                                    struct pack_window **w_curs,
 913                                    unsigned long offset,
 914                                    enum object_type kind,
 915                                    unsigned long delta_obj_offset,
 916                                    unsigned long *base_obj_offset)
 917{
 918        unsigned char *base_info = use_pack(p, w_curs, offset, NULL);
 919        unsigned long base_offset;
 920
 921        /* use_pack() assured us we have [base_info, base_info + 20)
 922         * as a range that we can look at without walking off the
 923         * end of the mapped window.  Its actually the hash size
 924         * that is assured.  An OFS_DELTA longer than the hash size
 925         * is stupid, as then a REF_DELTA would be smaller to store.
 926         */
 927        if (kind == OBJ_OFS_DELTA) {
 928                unsigned used = 0;
 929                unsigned char c = base_info[used++];
 930                base_offset = c & 127;
 931                while (c & 128) {
 932                        base_offset += 1;
 933                        if (!base_offset || base_offset & ~(~0UL >> 7))
 934                                die("offset value overflow for delta base object");
 935                        c = base_info[used++];
 936                        base_offset = (base_offset << 7) + (c & 127);
 937                }
 938                base_offset = delta_obj_offset - base_offset;
 939                if (base_offset >= delta_obj_offset)
 940                        die("delta base offset out of bound");
 941                offset += used;
 942        } else if (kind == OBJ_REF_DELTA) {
 943                /* The base entry _must_ be in the same pack */
 944                base_offset = find_pack_entry_one(base_info, p);
 945                if (!base_offset)
 946                        die("failed to find delta-pack base object %s",
 947                                sha1_to_hex(base_info));
 948                offset += 20;
 949        } else
 950                die("I am totally screwed");
 951        *base_obj_offset = base_offset;
 952        return offset;
 953}
 954
 955/* forward declaration for a mutually recursive function */
 956static int packed_object_info(struct packed_git *p, unsigned long offset,
 957                              char *type, unsigned long *sizep);
 958
 959static int packed_delta_info(struct packed_git *p,
 960                             struct pack_window **w_curs,
 961                             unsigned long offset,
 962                             enum object_type kind,
 963                             unsigned long obj_offset,
 964                             char *type,
 965                             unsigned long *sizep)
 966{
 967        unsigned long base_offset;
 968
 969        offset = get_delta_base(p, w_curs, offset, kind,
 970                obj_offset, &base_offset);
 971
 972        /* We choose to only get the type of the base object and
 973         * ignore potentially corrupt pack file that expects the delta
 974         * based on a base with a wrong size.  This saves tons of
 975         * inflate() calls.
 976         */
 977        if (packed_object_info(p, base_offset, type, NULL))
 978                die("cannot get info for delta-pack base");
 979
 980        if (sizep) {
 981                const unsigned char *data;
 982                unsigned char delta_head[20], *in;
 983                unsigned long result_size;
 984                z_stream stream;
 985                int st;
 986
 987                memset(&stream, 0, sizeof(stream));
 988                stream.next_out = delta_head;
 989                stream.avail_out = sizeof(delta_head);
 990
 991                inflateInit(&stream);
 992                do {
 993                        in = use_pack(p, w_curs, offset, &stream.avail_in);
 994                        stream.next_in = in;
 995                        st = inflate(&stream, Z_FINISH);
 996                        offset += stream.next_in - in;
 997                } while ((st == Z_OK || st == Z_BUF_ERROR)
 998                        && stream.total_out < sizeof(delta_head));
 999                inflateEnd(&stream);
1000                if ((st != Z_STREAM_END) &&
1001                    stream.total_out != sizeof(delta_head))
1002                        die("delta data unpack-initial failed");
1003
1004                /* Examine the initial part of the delta to figure out
1005                 * the result size.
1006                 */
1007                data = delta_head;
1008
1009                /* ignore base size */
1010                get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1011
1012                /* Read the result size */
1013                result_size = get_delta_hdr_size(&data, delta_head+sizeof(delta_head));
1014                *sizep = result_size;
1015        }
1016        return 0;
1017}
1018
1019static unsigned long unpack_object_header(struct packed_git *p,
1020                struct pack_window **w_curs,
1021                unsigned long offset,
1022                enum object_type *type,
1023                unsigned long *sizep)
1024{
1025        unsigned char *base;
1026        unsigned int left;
1027        unsigned long used;
1028
1029        /* use_pack() assures us we have [base, base + 20) available
1030         * as a range that we can look at at.  (Its actually the hash
1031         * size that is assurred.)  With our object header encoding
1032         * the maximum deflated object size is 2^137, which is just
1033         * insane, so we know won't exceed what we have been given.
1034         */
1035        base = use_pack(p, w_curs, offset, &left);
1036        used = unpack_object_header_gently(base, left, type, sizep);
1037        if (!used)
1038                die("object offset outside of pack file");
1039
1040        return offset + used;
1041}
1042
1043void packed_object_info_detail(struct packed_git *p,
1044                               unsigned long offset,
1045                               char *type,
1046                               unsigned long *size,
1047                               unsigned long *store_size,
1048                               unsigned int *delta_chain_length,
1049                               unsigned char *base_sha1)
1050{
1051        struct pack_window *w_curs = NULL;
1052        unsigned long obj_offset, val;
1053        unsigned char *next_sha1;
1054        enum object_type kind;
1055
1056        *delta_chain_length = 0;
1057        obj_offset = offset;
1058        offset = unpack_object_header(p, &w_curs, offset, &kind, size);
1059
1060        for (;;) {
1061                switch (kind) {
1062                default:
1063                        die("pack %s contains unknown object type %d",
1064                            p->pack_name, kind);
1065                case OBJ_COMMIT:
1066                case OBJ_TREE:
1067                case OBJ_BLOB:
1068                case OBJ_TAG:
1069                        strcpy(type, type_names[kind]);
1070                        *store_size = 0; /* notyet */
1071                        unuse_pack(&w_curs);
1072                        return;
1073                case OBJ_OFS_DELTA:
1074                        get_delta_base(p, &w_curs, offset, kind,
1075                                obj_offset, &offset);
1076                        if (*delta_chain_length == 0) {
1077                                /* TODO: find base_sha1 as pointed by offset */
1078                        }
1079                        break;
1080                case OBJ_REF_DELTA:
1081                        next_sha1 = use_pack(p, &w_curs, offset, NULL);
1082                        if (*delta_chain_length == 0)
1083                                hashcpy(base_sha1, next_sha1);
1084                        offset = find_pack_entry_one(next_sha1, p);
1085                        break;
1086                }
1087                obj_offset = offset;
1088                offset = unpack_object_header(p, &w_curs, offset, &kind, &val);
1089                (*delta_chain_length)++;
1090        }
1091}
1092
1093static int packed_object_info(struct packed_git *p, unsigned long offset,
1094                              char *type, unsigned long *sizep)
1095{
1096        struct pack_window *w_curs = NULL;
1097        unsigned long size, obj_offset = offset;
1098        enum object_type kind;
1099        int r;
1100
1101        offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1102
1103        switch (kind) {
1104        case OBJ_OFS_DELTA:
1105        case OBJ_REF_DELTA:
1106                r = packed_delta_info(p, &w_curs, offset, kind,
1107                        obj_offset, type, sizep);
1108                unuse_pack(&w_curs);
1109                return r;
1110        case OBJ_COMMIT:
1111        case OBJ_TREE:
1112        case OBJ_BLOB:
1113        case OBJ_TAG:
1114                strcpy(type, type_names[kind]);
1115                unuse_pack(&w_curs);
1116                break;
1117        default:
1118                die("pack %s contains unknown object type %d",
1119                    p->pack_name, kind);
1120        }
1121        if (sizep)
1122                *sizep = size;
1123        return 0;
1124}
1125
1126static void *unpack_compressed_entry(struct packed_git *p,
1127                                    struct pack_window **w_curs,
1128                                    unsigned long offset,
1129                                    unsigned long size)
1130{
1131        int st;
1132        z_stream stream;
1133        unsigned char *buffer, *in;
1134
1135        buffer = xmalloc(size + 1);
1136        buffer[size] = 0;
1137        memset(&stream, 0, sizeof(stream));
1138        stream.next_out = buffer;
1139        stream.avail_out = size;
1140
1141        inflateInit(&stream);
1142        do {
1143                in = use_pack(p, w_curs, offset, &stream.avail_in);
1144                stream.next_in = in;
1145                st = inflate(&stream, Z_FINISH);
1146                offset += stream.next_in - in;
1147        } while (st == Z_OK || st == Z_BUF_ERROR);
1148        inflateEnd(&stream);
1149        if ((st != Z_STREAM_END) || stream.total_out != size) {
1150                free(buffer);
1151                return NULL;
1152        }
1153
1154        return buffer;
1155}
1156
1157static void *unpack_delta_entry(struct packed_git *p,
1158                                struct pack_window **w_curs,
1159                                unsigned long offset,
1160                                unsigned long delta_size,
1161                                enum object_type kind,
1162                                unsigned long obj_offset,
1163                                char *type,
1164                                unsigned long *sizep)
1165{
1166        void *delta_data, *result, *base;
1167        unsigned long result_size, base_size, base_offset;
1168
1169        offset = get_delta_base(p, w_curs, offset, kind,
1170                obj_offset, &base_offset);
1171        base = unpack_entry(p, base_offset, type, &base_size);
1172        if (!base)
1173                die("failed to read delta base object at %lu from %s",
1174                    base_offset, p->pack_name);
1175
1176        delta_data = unpack_compressed_entry(p, w_curs, offset, delta_size);
1177        result = patch_delta(base, base_size,
1178                             delta_data, delta_size,
1179                             &result_size);
1180        if (!result)
1181                die("failed to apply delta");
1182        free(delta_data);
1183        free(base);
1184        *sizep = result_size;
1185        return result;
1186}
1187
1188void *unpack_entry(struct packed_git *p, unsigned long offset,
1189                          char *type, unsigned long *sizep)
1190{
1191        struct pack_window *w_curs = NULL;
1192        unsigned long size, obj_offset = offset;
1193        enum object_type kind;
1194        void *retval;
1195
1196        offset = unpack_object_header(p, &w_curs, offset, &kind, &size);
1197        switch (kind) {
1198        case OBJ_OFS_DELTA:
1199        case OBJ_REF_DELTA:
1200                retval = unpack_delta_entry(p, &w_curs, offset, size,
1201                        kind, obj_offset, type, sizep);
1202                break;
1203        case OBJ_COMMIT:
1204        case OBJ_TREE:
1205        case OBJ_BLOB:
1206        case OBJ_TAG:
1207                strcpy(type, type_names[kind]);
1208                *sizep = size;
1209                retval = unpack_compressed_entry(p, &w_curs, offset, size);
1210                break;
1211        default:
1212                die("unknown object type %i in %s", kind, p->pack_name);
1213        }
1214        unuse_pack(&w_curs);
1215        return retval;
1216}
1217
1218int num_packed_objects(const struct packed_git *p)
1219{
1220        /* See check_packed_git_idx() */
1221        return (p->index_size - 20 - 20 - 4*256) / 24;
1222}
1223
1224int nth_packed_object_sha1(const struct packed_git *p, int n,
1225                           unsigned char* sha1)
1226{
1227        void *index = p->index_base + 256;
1228        if (n < 0 || num_packed_objects(p) <= n)
1229                return -1;
1230        hashcpy(sha1, (unsigned char *) index + (24 * n) + 4);
1231        return 0;
1232}
1233
1234unsigned long find_pack_entry_one(const unsigned char *sha1,
1235                                  struct packed_git *p)
1236{
1237        unsigned int *level1_ofs = p->index_base;
1238        int hi = ntohl(level1_ofs[*sha1]);
1239        int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
1240        void *index = p->index_base + 256;
1241
1242        do {
1243                int mi = (lo + hi) / 2;
1244                int cmp = hashcmp((unsigned char *)index + (24 * mi) + 4, sha1);
1245                if (!cmp)
1246                        return ntohl(*((unsigned int *) ((char *) index + (24 * mi))));
1247                if (cmp > 0)
1248                        hi = mi;
1249                else
1250                        lo = mi+1;
1251        } while (lo < hi);
1252        return 0;
1253}
1254
1255static int matches_pack_name(struct packed_git *p, const char *ig)
1256{
1257        const char *last_c, *c;
1258
1259        if (!strcmp(p->pack_name, ig))
1260                return 0;
1261
1262        for (c = p->pack_name, last_c = c; *c;)
1263                if (*c == '/')
1264                        last_c = ++c;
1265                else
1266                        ++c;
1267        if (!strcmp(last_c, ig))
1268                return 0;
1269
1270        return 1;
1271}
1272
1273static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e, const char **ignore_packed)
1274{
1275        struct packed_git *p;
1276        unsigned long offset;
1277
1278        prepare_packed_git();
1279
1280        for (p = packed_git; p; p = p->next) {
1281                if (ignore_packed) {
1282                        const char **ig;
1283                        for (ig = ignore_packed; *ig; ig++)
1284                                if (!matches_pack_name(p, *ig))
1285                                        break;
1286                        if (*ig)
1287                                continue;
1288                }
1289                offset = find_pack_entry_one(sha1, p);
1290                if (offset) {
1291                        e->offset = offset;
1292                        e->p = p;
1293                        hashcpy(e->sha1, sha1);
1294                        return 1;
1295                }
1296        }
1297        return 0;
1298}
1299
1300struct packed_git *find_sha1_pack(const unsigned char *sha1, 
1301                                  struct packed_git *packs)
1302{
1303        struct packed_git *p;
1304
1305        for (p = packs; p; p = p->next) {
1306                if (find_pack_entry_one(sha1, p))
1307                        return p;
1308        }
1309        return NULL;
1310        
1311}
1312
1313static int sha1_loose_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1314{
1315        int status;
1316        unsigned long mapsize, size;
1317        void *map;
1318        z_stream stream;
1319        char hdr[128];
1320
1321        map = map_sha1_file(sha1, &mapsize);
1322        if (!map)
1323                return error("unable to find %s", sha1_to_hex(sha1));
1324        if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
1325                status = error("unable to unpack %s header",
1326                               sha1_to_hex(sha1));
1327        if (parse_sha1_header(hdr, type, &size) < 0)
1328                status = error("unable to parse %s header", sha1_to_hex(sha1));
1329        else {
1330                status = 0;
1331                if (sizep)
1332                        *sizep = size;
1333        }
1334        inflateEnd(&stream);
1335        munmap(map, mapsize);
1336        return status;
1337}
1338
1339int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
1340{
1341        struct pack_entry e;
1342
1343        if (!find_pack_entry(sha1, &e, NULL)) {
1344                reprepare_packed_git();
1345                if (!find_pack_entry(sha1, &e, NULL))
1346                        return sha1_loose_object_info(sha1, type, sizep);
1347        }
1348        return packed_object_info(e.p, e.offset, type, sizep);
1349}
1350
1351static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
1352{
1353        struct pack_entry e;
1354
1355        if (!find_pack_entry(sha1, &e, NULL)) {
1356                error("cannot read sha1_file for %s", sha1_to_hex(sha1));
1357                return NULL;
1358        }
1359        return unpack_entry(e.p, e.offset, type, size);
1360}
1361
1362void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
1363{
1364        unsigned long mapsize;
1365        void *map, *buf;
1366        struct pack_entry e;
1367
1368        if (find_pack_entry(sha1, &e, NULL))
1369                return read_packed_sha1(sha1, type, size);
1370        map = map_sha1_file(sha1, &mapsize);
1371        if (map) {
1372                buf = unpack_sha1_file(map, mapsize, type, size);
1373                munmap(map, mapsize);
1374                return buf;
1375        }
1376        reprepare_packed_git();
1377        if (find_pack_entry(sha1, &e, NULL))
1378                return read_packed_sha1(sha1, type, size);
1379        return NULL;
1380}
1381
1382void *read_object_with_reference(const unsigned char *sha1,
1383                                 const char *required_type,
1384                                 unsigned long *size,
1385                                 unsigned char *actual_sha1_return)
1386{
1387        char type[20];
1388        void *buffer;
1389        unsigned long isize;
1390        unsigned char actual_sha1[20];
1391
1392        hashcpy(actual_sha1, sha1);
1393        while (1) {
1394                int ref_length = -1;
1395                const char *ref_type = NULL;
1396
1397                buffer = read_sha1_file(actual_sha1, type, &isize);
1398                if (!buffer)
1399                        return NULL;
1400                if (!strcmp(type, required_type)) {
1401                        *size = isize;
1402                        if (actual_sha1_return)
1403                                hashcpy(actual_sha1_return, actual_sha1);
1404                        return buffer;
1405                }
1406                /* Handle references */
1407                else if (!strcmp(type, commit_type))
1408                        ref_type = "tree ";
1409                else if (!strcmp(type, tag_type))
1410                        ref_type = "object ";
1411                else {
1412                        free(buffer);
1413                        return NULL;
1414                }
1415                ref_length = strlen(ref_type);
1416
1417                if (memcmp(buffer, ref_type, ref_length) ||
1418                    get_sha1_hex((char *) buffer + ref_length, actual_sha1)) {
1419                        free(buffer);
1420                        return NULL;
1421                }
1422                free(buffer);
1423                /* Now we have the ID of the referred-to object in
1424                 * actual_sha1.  Check again. */
1425        }
1426}
1427
1428static void write_sha1_file_prepare(void *buf, unsigned long len,
1429                                    const char *type, unsigned char *sha1,
1430                                    unsigned char *hdr, int *hdrlen)
1431{
1432        SHA_CTX c;
1433
1434        /* Generate the header */
1435        *hdrlen = sprintf((char *)hdr, "%s %lu", type, len)+1;
1436
1437        /* Sha1.. */
1438        SHA1_Init(&c);
1439        SHA1_Update(&c, hdr, *hdrlen);
1440        SHA1_Update(&c, buf, len);
1441        SHA1_Final(sha1, &c);
1442}
1443
1444/*
1445 * Link the tempfile to the final place, possibly creating the
1446 * last directory level as you do so.
1447 *
1448 * Returns the errno on failure, 0 on success.
1449 */
1450static int link_temp_to_file(const char *tmpfile, const char *filename)
1451{
1452        int ret;
1453        char *dir;
1454
1455        if (!link(tmpfile, filename))
1456                return 0;
1457
1458        /*
1459         * Try to mkdir the last path component if that failed.
1460         *
1461         * Re-try the "link()" regardless of whether the mkdir
1462         * succeeds, since a race might mean that somebody
1463         * else succeeded.
1464         */
1465        ret = errno;
1466        dir = strrchr(filename, '/');
1467        if (dir) {
1468                *dir = 0;
1469                if (!mkdir(filename, 0777) && adjust_shared_perm(filename)) {
1470                        *dir = '/';
1471                        return -2;
1472                }
1473                *dir = '/';
1474                if (!link(tmpfile, filename))
1475                        return 0;
1476                ret = errno;
1477        }
1478        return ret;
1479}
1480
1481/*
1482 * Move the just written object into its final resting place
1483 */
1484int move_temp_to_file(const char *tmpfile, const char *filename)
1485{
1486        int ret = link_temp_to_file(tmpfile, filename);
1487
1488        /*
1489         * Coda hack - coda doesn't like cross-directory links,
1490         * so we fall back to a rename, which will mean that it
1491         * won't be able to check collisions, but that's not a
1492         * big deal.
1493         *
1494         * The same holds for FAT formatted media.
1495         *
1496         * When this succeeds, we just return 0. We have nothing
1497         * left to unlink.
1498         */
1499        if (ret && ret != EEXIST) {
1500                if (!rename(tmpfile, filename))
1501                        return 0;
1502                ret = errno;
1503        }
1504        unlink(tmpfile);
1505        if (ret) {
1506                if (ret != EEXIST) {
1507                        return error("unable to write sha1 filename %s: %s\n", filename, strerror(ret));
1508                }
1509                /* FIXME!!! Collision check here ? */
1510        }
1511
1512        return 0;
1513}
1514
1515static int write_buffer(int fd, const void *buf, size_t len)
1516{
1517        while (len) {
1518                ssize_t size;
1519
1520                size = write(fd, buf, len);
1521                if (!size)
1522                        return error("file write: disk full");
1523                if (size < 0) {
1524                        if (errno == EINTR || errno == EAGAIN)
1525                                continue;
1526                        return error("file write error (%s)", strerror(errno));
1527                }
1528                len -= size;
1529                buf = (char *) buf + size;
1530        }
1531        return 0;
1532}
1533
1534static int write_binary_header(unsigned char *hdr, enum object_type type, unsigned long len)
1535{
1536        int hdr_len;
1537        unsigned char c;
1538
1539        c = (type << 4) | (len & 15);
1540        len >>= 4;
1541        hdr_len = 1;
1542        while (len) {
1543                *hdr++ = c | 0x80;
1544                hdr_len++;
1545                c = (len & 0x7f);
1546                len >>= 7;
1547        }
1548        *hdr = c;
1549        return hdr_len;
1550}
1551
1552static void setup_object_header(z_stream *stream, const char *type, unsigned long len)
1553{
1554        int obj_type, hdr;
1555
1556        if (use_legacy_headers) {
1557                while (deflate(stream, 0) == Z_OK)
1558                        /* nothing */;
1559                return;
1560        }
1561        if (!strcmp(type, blob_type))
1562                obj_type = OBJ_BLOB;
1563        else if (!strcmp(type, tree_type))
1564                obj_type = OBJ_TREE;
1565        else if (!strcmp(type, commit_type))
1566                obj_type = OBJ_COMMIT;
1567        else if (!strcmp(type, tag_type))
1568                obj_type = OBJ_TAG;
1569        else
1570                die("trying to generate bogus object of type '%s'", type);
1571        hdr = write_binary_header(stream->next_out, obj_type, len);
1572        stream->total_out = hdr;
1573        stream->next_out += hdr;
1574        stream->avail_out -= hdr;
1575}
1576
1577int hash_sha1_file(void *buf, unsigned long len, const char *type,
1578                   unsigned char *sha1)
1579{
1580        unsigned char hdr[50];
1581        int hdrlen;
1582        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1583        return 0;
1584}
1585
1586int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
1587{
1588        int size;
1589        unsigned char *compressed;
1590        z_stream stream;
1591        unsigned char sha1[20];
1592        char *filename;
1593        static char tmpfile[PATH_MAX];
1594        unsigned char hdr[50];
1595        int fd, hdrlen;
1596
1597        /* Normally if we have it in the pack then we do not bother writing
1598         * it out into .git/objects/??/?{38} file.
1599         */
1600        write_sha1_file_prepare(buf, len, type, sha1, hdr, &hdrlen);
1601        filename = sha1_file_name(sha1);
1602        if (returnsha1)
1603                hashcpy(returnsha1, sha1);
1604        if (has_sha1_file(sha1))
1605                return 0;
1606        fd = open(filename, O_RDONLY);
1607        if (fd >= 0) {
1608                /*
1609                 * FIXME!!! We might do collision checking here, but we'd
1610                 * need to uncompress the old file and check it. Later.
1611                 */
1612                close(fd);
1613                return 0;
1614        }
1615
1616        if (errno != ENOENT) {
1617                return error("sha1 file %s: %s\n", filename, strerror(errno));
1618        }
1619
1620        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1621
1622        fd = mkstemp(tmpfile);
1623        if (fd < 0) {
1624                if (errno == EPERM)
1625                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1626                else
1627                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1628        }
1629
1630        /* Set it up */
1631        memset(&stream, 0, sizeof(stream));
1632        deflateInit(&stream, zlib_compression_level);
1633        size = 8 + deflateBound(&stream, len+hdrlen);
1634        compressed = xmalloc(size);
1635
1636        /* Compress it */
1637        stream.next_out = compressed;
1638        stream.avail_out = size;
1639
1640        /* First header.. */
1641        stream.next_in = hdr;
1642        stream.avail_in = hdrlen;
1643        setup_object_header(&stream, type, len);
1644
1645        /* Then the data itself.. */
1646        stream.next_in = buf;
1647        stream.avail_in = len;
1648        while (deflate(&stream, Z_FINISH) == Z_OK)
1649                /* nothing */;
1650        deflateEnd(&stream);
1651        size = stream.total_out;
1652
1653        if (write_buffer(fd, compressed, size) < 0)
1654                die("unable to write sha1 file");
1655        fchmod(fd, 0444);
1656        close(fd);
1657        free(compressed);
1658
1659        return move_temp_to_file(tmpfile, filename);
1660}
1661
1662/*
1663 * We need to unpack and recompress the object for writing
1664 * it out to a different file.
1665 */
1666static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
1667{
1668        size_t size;
1669        z_stream stream;
1670        unsigned char *unpacked;
1671        unsigned long len;
1672        char type[20];
1673        char hdr[50];
1674        int hdrlen;
1675        void *buf;
1676
1677        /* need to unpack and recompress it by itself */
1678        unpacked = read_packed_sha1(sha1, type, &len);
1679
1680        hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
1681
1682        /* Set it up */
1683        memset(&stream, 0, sizeof(stream));
1684        deflateInit(&stream, zlib_compression_level);
1685        size = deflateBound(&stream, len + hdrlen);
1686        buf = xmalloc(size);
1687
1688        /* Compress it */
1689        stream.next_out = buf;
1690        stream.avail_out = size;
1691
1692        /* First header.. */
1693        stream.next_in = (void *)hdr;
1694        stream.avail_in = hdrlen;
1695        while (deflate(&stream, 0) == Z_OK)
1696                /* nothing */;
1697
1698        /* Then the data itself.. */
1699        stream.next_in = unpacked;
1700        stream.avail_in = len;
1701        while (deflate(&stream, Z_FINISH) == Z_OK)
1702                /* nothing */;
1703        deflateEnd(&stream);
1704        free(unpacked);
1705
1706        *objsize = stream.total_out;
1707        return buf;
1708}
1709
1710int write_sha1_to_fd(int fd, const unsigned char *sha1)
1711{
1712        int retval;
1713        unsigned long objsize;
1714        void *buf = map_sha1_file(sha1, &objsize);
1715
1716        if (buf) {
1717                retval = write_buffer(fd, buf, objsize);
1718                munmap(buf, objsize);
1719                return retval;
1720        }
1721
1722        buf = repack_object(sha1, &objsize);
1723        retval = write_buffer(fd, buf, objsize);
1724        free(buf);
1725        return retval;
1726}
1727
1728int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
1729                       size_t bufsize, size_t *bufposn)
1730{
1731        char tmpfile[PATH_MAX];
1732        int local;
1733        z_stream stream;
1734        unsigned char real_sha1[20];
1735        unsigned char discard[4096];
1736        int ret;
1737        SHA_CTX c;
1738
1739        snprintf(tmpfile, sizeof(tmpfile), "%s/obj_XXXXXX", get_object_directory());
1740
1741        local = mkstemp(tmpfile);
1742        if (local < 0) {
1743                if (errno == EPERM)
1744                        return error("insufficient permission for adding an object to repository database %s\n", get_object_directory());
1745                else
1746                        return error("unable to create temporary sha1 filename %s: %s\n", tmpfile, strerror(errno));
1747        }
1748
1749        memset(&stream, 0, sizeof(stream));
1750
1751        inflateInit(&stream);
1752
1753        SHA1_Init(&c);
1754
1755        do {
1756                ssize_t size;
1757                if (*bufposn) {
1758                        stream.avail_in = *bufposn;
1759                        stream.next_in = (unsigned char *) buffer;
1760                        do {
1761                                stream.next_out = discard;
1762                                stream.avail_out = sizeof(discard);
1763                                ret = inflate(&stream, Z_SYNC_FLUSH);
1764                                SHA1_Update(&c, discard, sizeof(discard) -
1765                                            stream.avail_out);
1766                        } while (stream.avail_in && ret == Z_OK);
1767                        if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
1768                                die("unable to write sha1 file");
1769                        memmove(buffer, buffer + *bufposn - stream.avail_in,
1770                                stream.avail_in);
1771                        *bufposn = stream.avail_in;
1772                        if (ret != Z_OK)
1773                                break;
1774                }
1775                size = read(fd, buffer + *bufposn, bufsize - *bufposn);
1776                if (size <= 0) {
1777                        close(local);
1778                        unlink(tmpfile);
1779                        if (!size)
1780                                return error("Connection closed?");
1781                        perror("Reading from connection");
1782                        return -1;
1783                }
1784                *bufposn += size;
1785        } while (1);
1786        inflateEnd(&stream);
1787
1788        close(local);
1789        SHA1_Final(real_sha1, &c);
1790        if (ret != Z_STREAM_END) {
1791                unlink(tmpfile);
1792                return error("File %s corrupted", sha1_to_hex(sha1));
1793        }
1794        if (hashcmp(sha1, real_sha1)) {
1795                unlink(tmpfile);
1796                return error("File %s has bad hash", sha1_to_hex(sha1));
1797        }
1798
1799        return move_temp_to_file(tmpfile, sha1_file_name(sha1));
1800}
1801
1802int has_pack_index(const unsigned char *sha1)
1803{
1804        struct stat st;
1805        if (stat(sha1_pack_index_name(sha1), &st))
1806                return 0;
1807        return 1;
1808}
1809
1810int has_pack_file(const unsigned char *sha1)
1811{
1812        struct stat st;
1813        if (stat(sha1_pack_name(sha1), &st))
1814                return 0;
1815        return 1;
1816}
1817
1818int has_sha1_pack(const unsigned char *sha1, const char **ignore_packed)
1819{
1820        struct pack_entry e;
1821        return find_pack_entry(sha1, &e, ignore_packed);
1822}
1823
1824int has_sha1_file(const unsigned char *sha1)
1825{
1826        struct stat st;
1827        struct pack_entry e;
1828
1829        if (find_pack_entry(sha1, &e, NULL))
1830                return 1;
1831        return find_sha1_file(sha1, &st) ? 1 : 0;
1832}
1833
1834/*
1835 * reads from fd as long as possible into a supplied buffer of size bytes.
1836 * If necessary the buffer's size is increased using realloc()
1837 *
1838 * returns 0 if anything went fine and -1 otherwise
1839 *
1840 * NOTE: both buf and size may change, but even when -1 is returned
1841 * you still have to free() it yourself.
1842 */
1843int read_pipe(int fd, char** return_buf, unsigned long* return_size)
1844{
1845        char* buf = *return_buf;
1846        unsigned long size = *return_size;
1847        int iret;
1848        unsigned long off = 0;
1849
1850        do {
1851                iret = xread(fd, buf + off, size - off);
1852                if (iret > 0) {
1853                        off += iret;
1854                        if (off == size) {
1855                                size *= 2;
1856                                buf = xrealloc(buf, size);
1857                        }
1858                }
1859        } while (iret > 0);
1860
1861        *return_buf = buf;
1862        *return_size = off;
1863
1864        if (iret < 0)
1865                return -1;
1866        return 0;
1867}
1868
1869int index_pipe(unsigned char *sha1, int fd, const char *type, int write_object)
1870{
1871        unsigned long size = 4096;
1872        char *buf = xmalloc(size);
1873        int ret;
1874
1875        if (read_pipe(fd, &buf, &size)) {
1876                free(buf);
1877                return -1;
1878        }
1879
1880        if (!type)
1881                type = blob_type;
1882        if (write_object)
1883                ret = write_sha1_file(buf, size, type, sha1);
1884        else
1885                ret = hash_sha1_file(buf, size, type, sha1);
1886        free(buf);
1887        return ret;
1888}
1889
1890int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, const char *type)
1891{
1892        unsigned long size = st->st_size;
1893        void *buf;
1894        int ret;
1895
1896        buf = "";
1897        if (size)
1898                buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
1899        close(fd);
1900        if (buf == MAP_FAILED)
1901                return -1;
1902
1903        if (!type)
1904                type = blob_type;
1905        if (write_object)
1906                ret = write_sha1_file(buf, size, type, sha1);
1907        else
1908                ret = hash_sha1_file(buf, size, type, sha1);
1909        if (size)
1910                munmap(buf, size);
1911        return ret;
1912}
1913
1914int index_path(unsigned char *sha1, const char *path, struct stat *st, int write_object)
1915{
1916        int fd;
1917        char *target;
1918
1919        switch (st->st_mode & S_IFMT) {
1920        case S_IFREG:
1921                fd = open(path, O_RDONLY);
1922                if (fd < 0)
1923                        return error("open(\"%s\"): %s", path,
1924                                     strerror(errno));
1925                if (index_fd(sha1, fd, st, write_object, NULL) < 0)
1926                        return error("%s: failed to insert into database",
1927                                     path);
1928                break;
1929        case S_IFLNK:
1930                target = xmalloc(st->st_size+1);
1931                if (readlink(path, target, st->st_size+1) != st->st_size) {
1932                        char *errstr = strerror(errno);
1933                        free(target);
1934                        return error("readlink(\"%s\"): %s", path,
1935                                     errstr);
1936                }
1937                if (!write_object)
1938                        hash_sha1_file(target, st->st_size, blob_type, sha1);
1939                else if (write_sha1_file(target, st->st_size, blob_type, sha1))
1940                        return error("%s: failed to insert into database",
1941                                     path);
1942                free(target);
1943                break;
1944        default:
1945                return error("%s: unsupported file type", path);
1946        }
1947        return 0;
1948}