builtin-pack-objects.con commit Custom compression levels for objects and packs (960ccca)
   1#include "builtin.h"
   2#include "cache.h"
   3#include "object.h"
   4#include "blob.h"
   5#include "commit.h"
   6#include "tag.h"
   7#include "tree.h"
   8#include "delta.h"
   9#include "pack.h"
  10#include "csum-file.h"
  11#include "tree-walk.h"
  12#include "diff.h"
  13#include "revision.h"
  14#include "list-objects.h"
  15#include "progress.h"
  16
  17static const char pack_usage[] = "\
  18git-pack-objects [{ -q | --progress | --all-progress }] \n\
  19        [--local] [--incremental] [--window=N] [--depth=N] \n\
  20        [--no-reuse-delta] [--no-reuse-object] [--delta-base-offset] \n\
  21        [--non-empty] [--revs [--unpacked | --all]*] [--reflog] \n\
  22        [--stdout | base-name] [<ref-list | <object-list]";
  23
  24struct object_entry {
  25        unsigned char sha1[20];
  26        uint32_t crc32;         /* crc of raw pack data for this object */
  27        off_t offset;           /* offset into the final pack file */
  28        unsigned long size;     /* uncompressed size */
  29        unsigned int hash;      /* name hint hash */
  30        unsigned int depth;     /* delta depth */
  31        struct packed_git *in_pack;     /* already in pack */
  32        off_t in_pack_offset;
  33        struct object_entry *delta;     /* delta base object */
  34        struct object_entry *delta_child; /* deltified objects who bases me */
  35        struct object_entry *delta_sibling; /* other deltified objects who
  36                                             * uses the same base as me
  37                                             */
  38        unsigned long delta_size;       /* delta data size (uncompressed) */
  39        enum object_type type;
  40        enum object_type in_pack_type;  /* could be delta */
  41        unsigned char in_pack_header_size;
  42        unsigned char preferred_base; /* we do not pack this, but is available
  43                                       * to be used as the base objectto delta
  44                                       * objects against.
  45                                       */
  46};
  47
  48/*
  49 * Objects we are going to pack are collected in objects array (dynamically
  50 * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  51 * in the order we see -- typically rev-list --objects order that gives us
  52 * nice "minimum seek" order.
  53 */
  54static struct object_entry *objects;
  55static uint32_t nr_objects, nr_alloc, nr_result;
  56
  57static int non_empty;
  58static int no_reuse_delta, no_reuse_object;
  59static int local;
  60static int incremental;
  61static int allow_ofs_delta;
  62static const char *pack_tmp_name, *idx_tmp_name;
  63static char tmpname[PATH_MAX];
  64static unsigned char pack_file_sha1[20];
  65static int progress = 1;
  66static int window = 10;
  67static int depth = 50;
  68static int pack_to_stdout;
  69static int num_preferred_base;
  70static struct progress progress_state;
  71static int pack_compression_level = Z_DEFAULT_COMPRESSION;
  72static int pack_compression_seen;
  73
  74/*
  75 * The object names in objects array are hashed with this hashtable,
  76 * to help looking up the entry by object name.
  77 * This hashtable is built after all the objects are seen.
  78 */
  79static int *object_ix;
  80static int object_ix_hashsz;
  81
  82/*
  83 * Pack index for existing packs give us easy access to the offsets into
  84 * corresponding pack file where each object's data starts, but the entries
  85 * do not store the size of the compressed representation (uncompressed
  86 * size is easily available by examining the pack entry header).  It is
  87 * also rather expensive to find the sha1 for an object given its offset.
  88 *
  89 * We build a hashtable of existing packs (pack_revindex), and keep reverse
  90 * index here -- pack index file is sorted by object name mapping to offset;
  91 * this pack_revindex[].revindex array is a list of offset/index_nr pairs
  92 * ordered by offset, so if you know the offset of an object, next offset
  93 * is where its packed representation ends and the index_nr can be used to
  94 * get the object sha1 from the main index.
  95 */
  96struct revindex_entry {
  97        off_t offset;
  98        unsigned int nr;
  99};
 100struct pack_revindex {
 101        struct packed_git *p;
 102        struct revindex_entry *revindex;
 103};
 104static struct  pack_revindex *pack_revindex;
 105static int pack_revindex_hashsz;
 106
 107/*
 108 * stats
 109 */
 110static uint32_t written, written_delta;
 111static uint32_t reused, reused_delta;
 112
 113static int pack_revindex_ix(struct packed_git *p)
 114{
 115        unsigned long ui = (unsigned long)p;
 116        int i;
 117
 118        ui = ui ^ (ui >> 16); /* defeat structure alignment */
 119        i = (int)(ui % pack_revindex_hashsz);
 120        while (pack_revindex[i].p) {
 121                if (pack_revindex[i].p == p)
 122                        return i;
 123                if (++i == pack_revindex_hashsz)
 124                        i = 0;
 125        }
 126        return -1 - i;
 127}
 128
 129static void prepare_pack_ix(void)
 130{
 131        int num;
 132        struct packed_git *p;
 133        for (num = 0, p = packed_git; p; p = p->next)
 134                num++;
 135        if (!num)
 136                return;
 137        pack_revindex_hashsz = num * 11;
 138        pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 139        for (p = packed_git; p; p = p->next) {
 140                num = pack_revindex_ix(p);
 141                num = - 1 - num;
 142                pack_revindex[num].p = p;
 143        }
 144        /* revindex elements are lazily initialized */
 145}
 146
 147static int cmp_offset(const void *a_, const void *b_)
 148{
 149        const struct revindex_entry *a = a_;
 150        const struct revindex_entry *b = b_;
 151        return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
 152}
 153
 154/*
 155 * Ordered list of offsets of objects in the pack.
 156 */
 157static void prepare_pack_revindex(struct pack_revindex *rix)
 158{
 159        struct packed_git *p = rix->p;
 160        int num_ent = p->num_objects;
 161        int i;
 162        const char *index = p->index_data;
 163
 164        rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
 165        index += 4 * 256;
 166
 167        if (p->index_version > 1) {
 168                const uint32_t *off_32 =
 169                        (uint32_t *)(index + 8 + p->num_objects * (20 + 4));
 170                const uint32_t *off_64 = off_32 + p->num_objects;
 171                for (i = 0; i < num_ent; i++) {
 172                        uint32_t off = ntohl(*off_32++);
 173                        if (!(off & 0x80000000)) {
 174                                rix->revindex[i].offset = off;
 175                        } else {
 176                                rix->revindex[i].offset =
 177                                        ((uint64_t)ntohl(*off_64++)) << 32;
 178                                rix->revindex[i].offset |=
 179                                        ntohl(*off_64++);
 180                        }
 181                        rix->revindex[i].nr = i;
 182                }
 183        } else {
 184                for (i = 0; i < num_ent; i++) {
 185                        uint32_t hl = *((uint32_t *)(index + 24 * i));
 186                        rix->revindex[i].offset = ntohl(hl);
 187                        rix->revindex[i].nr = i;
 188                }
 189        }
 190
 191        /* This knows the pack format -- the 20-byte trailer
 192         * follows immediately after the last object data.
 193         */
 194        rix->revindex[num_ent].offset = p->pack_size - 20;
 195        rix->revindex[num_ent].nr = -1;
 196        qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
 197}
 198
 199static struct revindex_entry * find_packed_object(struct packed_git *p,
 200                                                  off_t ofs)
 201{
 202        int num;
 203        int lo, hi;
 204        struct pack_revindex *rix;
 205        struct revindex_entry *revindex;
 206        num = pack_revindex_ix(p);
 207        if (num < 0)
 208                die("internal error: pack revindex uninitialized");
 209        rix = &pack_revindex[num];
 210        if (!rix->revindex)
 211                prepare_pack_revindex(rix);
 212        revindex = rix->revindex;
 213        lo = 0;
 214        hi = p->num_objects + 1;
 215        do {
 216                int mi = (lo + hi) / 2;
 217                if (revindex[mi].offset == ofs) {
 218                        return revindex + mi;
 219                }
 220                else if (ofs < revindex[mi].offset)
 221                        hi = mi;
 222                else
 223                        lo = mi + 1;
 224        } while (lo < hi);
 225        die("internal error: pack revindex corrupt");
 226}
 227
 228static const unsigned char *find_packed_object_name(struct packed_git *p,
 229                                                    off_t ofs)
 230{
 231        struct revindex_entry *entry = find_packed_object(p, ofs);
 232        return nth_packed_object_sha1(p, entry->nr);
 233}
 234
 235static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 236{
 237        unsigned long othersize, delta_size;
 238        enum object_type type;
 239        void *otherbuf = read_sha1_file(entry->delta->sha1, &type, &othersize);
 240        void *delta_buf;
 241
 242        if (!otherbuf)
 243                die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 244        delta_buf = diff_delta(otherbuf, othersize,
 245                               buf, size, &delta_size, 0);
 246        if (!delta_buf || delta_size != entry->delta_size)
 247                die("delta size changed");
 248        free(buf);
 249        free(otherbuf);
 250        return delta_buf;
 251}
 252
 253/*
 254 * The per-object header is a pretty dense thing, which is
 255 *  - first byte: low four bits are "size", then three bits of "type",
 256 *    and the high bit is "size continues".
 257 *  - each byte afterwards: low seven bits are size continuation,
 258 *    with the high bit being "size continues"
 259 */
 260static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 261{
 262        int n = 1;
 263        unsigned char c;
 264
 265        if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
 266                die("bad type %d", type);
 267
 268        c = (type << 4) | (size & 15);
 269        size >>= 4;
 270        while (size) {
 271                *hdr++ = c | 0x80;
 272                c = size & 0x7f;
 273                size >>= 7;
 274                n++;
 275        }
 276        *hdr = c;
 277        return n;
 278}
 279
 280/*
 281 * we are going to reuse the existing object data as is.  make
 282 * sure it is not corrupt.
 283 */
 284static int check_pack_inflate(struct packed_git *p,
 285                struct pack_window **w_curs,
 286                off_t offset,
 287                off_t len,
 288                unsigned long expect)
 289{
 290        z_stream stream;
 291        unsigned char fakebuf[4096], *in;
 292        int st;
 293
 294        memset(&stream, 0, sizeof(stream));
 295        inflateInit(&stream);
 296        do {
 297                in = use_pack(p, w_curs, offset, &stream.avail_in);
 298                stream.next_in = in;
 299                stream.next_out = fakebuf;
 300                stream.avail_out = sizeof(fakebuf);
 301                st = inflate(&stream, Z_FINISH);
 302                offset += stream.next_in - in;
 303        } while (st == Z_OK || st == Z_BUF_ERROR);
 304        inflateEnd(&stream);
 305        return (st == Z_STREAM_END &&
 306                stream.total_out == expect &&
 307                stream.total_in == len) ? 0 : -1;
 308}
 309
 310static int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
 311                          off_t offset, off_t len, unsigned int nr)
 312{
 313        const uint32_t *index_crc;
 314        uint32_t data_crc = crc32(0, Z_NULL, 0);
 315
 316        do {
 317                unsigned int avail;
 318                void *data = use_pack(p, w_curs, offset, &avail);
 319                if (avail > len)
 320                        avail = len;
 321                data_crc = crc32(data_crc, data, avail);
 322                offset += avail;
 323                len -= avail;
 324        } while (len);
 325
 326        index_crc = p->index_data;
 327        index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
 328
 329        return data_crc != ntohl(*index_crc);
 330}
 331
 332static void copy_pack_data(struct sha1file *f,
 333                struct packed_git *p,
 334                struct pack_window **w_curs,
 335                off_t offset,
 336                off_t len)
 337{
 338        unsigned char *in;
 339        unsigned int avail;
 340
 341        while (len) {
 342                in = use_pack(p, w_curs, offset, &avail);
 343                if (avail > len)
 344                        avail = (unsigned int)len;
 345                sha1write(f, in, avail);
 346                offset += avail;
 347                len -= avail;
 348        }
 349}
 350
 351static int check_loose_inflate(unsigned char *data, unsigned long len, unsigned long expect)
 352{
 353        z_stream stream;
 354        unsigned char fakebuf[4096];
 355        int st;
 356
 357        memset(&stream, 0, sizeof(stream));
 358        stream.next_in = data;
 359        stream.avail_in = len;
 360        stream.next_out = fakebuf;
 361        stream.avail_out = sizeof(fakebuf);
 362        inflateInit(&stream);
 363
 364        while (1) {
 365                st = inflate(&stream, Z_FINISH);
 366                if (st == Z_STREAM_END || st == Z_OK) {
 367                        st = (stream.total_out == expect &&
 368                              stream.total_in == len) ? 0 : -1;
 369                        break;
 370                }
 371                if (st != Z_BUF_ERROR) {
 372                        st = -1;
 373                        break;
 374                }
 375                stream.next_out = fakebuf;
 376                stream.avail_out = sizeof(fakebuf);
 377        }
 378        inflateEnd(&stream);
 379        return st;
 380}
 381
 382static int revalidate_loose_object(struct object_entry *entry,
 383                                   unsigned char *map,
 384                                   unsigned long mapsize)
 385{
 386        /* we already know this is a loose object with new type header. */
 387        enum object_type type;
 388        unsigned long size, used;
 389
 390        if (pack_to_stdout)
 391                return 0;
 392
 393        used = unpack_object_header_gently(map, mapsize, &type, &size);
 394        if (!used)
 395                return -1;
 396        map += used;
 397        mapsize -= used;
 398        return check_loose_inflate(map, mapsize, size);
 399}
 400
 401static unsigned long write_object(struct sha1file *f,
 402                                  struct object_entry *entry)
 403{
 404        unsigned long size;
 405        enum object_type type;
 406        void *buf;
 407        unsigned char header[10];
 408        unsigned hdrlen;
 409        off_t datalen;
 410        enum object_type obj_type;
 411        int to_reuse = 0;
 412
 413        if (!pack_to_stdout)
 414                crc32_begin(f);
 415
 416        obj_type = entry->type;
 417        if (no_reuse_object)
 418                to_reuse = 0;   /* explicit */
 419        else if (!entry->in_pack)
 420                to_reuse = 0;   /* can't reuse what we don't have */
 421        else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
 422                to_reuse = 1;   /* check_object() decided it for us */
 423        else if (obj_type != entry->in_pack_type)
 424                to_reuse = 0;   /* pack has delta which is unusable */
 425        else if (entry->delta)
 426                to_reuse = 0;   /* we want to pack afresh */
 427        else
 428                to_reuse = 1;   /* we have it in-pack undeltified,
 429                                 * and we do not need to deltify it.
 430                                 */
 431
 432        /* differing core & pack compression when loose object -> must recompress */
 433        if (!entry->in_pack && pack_compression_level != zlib_compression_level)
 434                to_reuse = 0;
 435        else if (!no_reuse_object && !entry->in_pack && !entry->delta) {
 436                unsigned char *map;
 437                unsigned long mapsize;
 438                map = map_sha1_file(entry->sha1, &mapsize);
 439                if (map && !legacy_loose_object(map)) {
 440                        /* We can copy straight into the pack file */
 441                        if (revalidate_loose_object(entry, map, mapsize))
 442                                die("corrupt loose object %s",
 443                                    sha1_to_hex(entry->sha1));
 444                        sha1write(f, map, mapsize);
 445                        munmap(map, mapsize);
 446                        written++;
 447                        reused++;
 448                        return mapsize;
 449                }
 450                if (map)
 451                        munmap(map, mapsize);
 452        }
 453
 454        if (!to_reuse) {
 455                buf = read_sha1_file(entry->sha1, &type, &size);
 456                if (!buf)
 457                        die("unable to read %s", sha1_to_hex(entry->sha1));
 458                if (size != entry->size)
 459                        die("object %s size inconsistency (%lu vs %lu)",
 460                            sha1_to_hex(entry->sha1), size, entry->size);
 461                if (entry->delta) {
 462                        buf = delta_against(buf, size, entry);
 463                        size = entry->delta_size;
 464                        obj_type = (allow_ofs_delta && entry->delta->offset) ?
 465                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 466                }
 467                /*
 468                 * The object header is a byte of 'type' followed by zero or
 469                 * more bytes of length.
 470                 */
 471                hdrlen = encode_header(obj_type, size, header);
 472                sha1write(f, header, hdrlen);
 473
 474                if (obj_type == OBJ_OFS_DELTA) {
 475                        /*
 476                         * Deltas with relative base contain an additional
 477                         * encoding of the relative offset for the delta
 478                         * base from this object's position in the pack.
 479                         */
 480                        off_t ofs = entry->offset - entry->delta->offset;
 481                        unsigned pos = sizeof(header) - 1;
 482                        header[pos] = ofs & 127;
 483                        while (ofs >>= 7)
 484                                header[--pos] = 128 | (--ofs & 127);
 485                        sha1write(f, header + pos, sizeof(header) - pos);
 486                        hdrlen += sizeof(header) - pos;
 487                } else if (obj_type == OBJ_REF_DELTA) {
 488                        /*
 489                         * Deltas with a base reference contain
 490                         * an additional 20 bytes for the base sha1.
 491                         */
 492                        sha1write(f, entry->delta->sha1, 20);
 493                        hdrlen += 20;
 494                }
 495                datalen = sha1write_compressed(f, buf, size, pack_compression_level);
 496                free(buf);
 497        }
 498        else {
 499                struct packed_git *p = entry->in_pack;
 500                struct pack_window *w_curs = NULL;
 501                struct revindex_entry *revidx;
 502                off_t offset;
 503
 504                if (entry->delta) {
 505                        obj_type = (allow_ofs_delta && entry->delta->offset) ?
 506                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 507                        reused_delta++;
 508                }
 509                hdrlen = encode_header(obj_type, entry->size, header);
 510                sha1write(f, header, hdrlen);
 511                if (obj_type == OBJ_OFS_DELTA) {
 512                        off_t ofs = entry->offset - entry->delta->offset;
 513                        unsigned pos = sizeof(header) - 1;
 514                        header[pos] = ofs & 127;
 515                        while (ofs >>= 7)
 516                                header[--pos] = 128 | (--ofs & 127);
 517                        sha1write(f, header + pos, sizeof(header) - pos);
 518                        hdrlen += sizeof(header) - pos;
 519                } else if (obj_type == OBJ_REF_DELTA) {
 520                        sha1write(f, entry->delta->sha1, 20);
 521                        hdrlen += 20;
 522                }
 523
 524                offset = entry->in_pack_offset;
 525                revidx = find_packed_object(p, offset);
 526                datalen = revidx[1].offset - offset;
 527                if (!pack_to_stdout && p->index_version > 1 &&
 528                    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
 529                        die("bad packed object CRC for %s", sha1_to_hex(entry->sha1));
 530                offset += entry->in_pack_header_size;
 531                datalen -= entry->in_pack_header_size;
 532                if (!pack_to_stdout && p->index_version == 1 &&
 533                    check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
 534                        die("corrupt packed object for %s", sha1_to_hex(entry->sha1));
 535                copy_pack_data(f, p, &w_curs, offset, datalen);
 536                unuse_pack(&w_curs);
 537                reused++;
 538        }
 539        if (entry->delta)
 540                written_delta++;
 541        written++;
 542        if (!pack_to_stdout)
 543                entry->crc32 = crc32_end(f);
 544        return hdrlen + datalen;
 545}
 546
 547static off_t write_one(struct sha1file *f,
 548                               struct object_entry *e,
 549                               off_t offset)
 550{
 551        unsigned long size;
 552
 553        /* offset is non zero if object is written already. */
 554        if (e->offset || e->preferred_base)
 555                return offset;
 556
 557        /* if we are deltified, write out base object first. */
 558        if (e->delta)
 559                offset = write_one(f, e->delta, offset);
 560
 561        e->offset = offset;
 562        size = write_object(f, e);
 563
 564        /* make sure off_t is sufficiently large not to wrap */
 565        if (offset > offset + size)
 566                die("pack too large for current definition of off_t");
 567        return offset + size;
 568}
 569
 570static int open_object_dir_tmp(const char *path)
 571{
 572    snprintf(tmpname, sizeof(tmpname), "%s/%s", get_object_directory(), path);
 573    return mkstemp(tmpname);
 574}
 575
 576static off_t write_pack_file(void)
 577{
 578        uint32_t i;
 579        struct sha1file *f;
 580        off_t offset, last_obj_offset = 0;
 581        struct pack_header hdr;
 582        int do_progress = progress;
 583
 584        if (pack_to_stdout) {
 585                f = sha1fd(1, "<stdout>");
 586                do_progress >>= 1;
 587        } else {
 588                int fd = open_object_dir_tmp("tmp_pack_XXXXXX");
 589                if (fd < 0)
 590                        die("unable to create %s: %s\n", tmpname, strerror(errno));
 591                pack_tmp_name = xstrdup(tmpname);
 592                f = sha1fd(fd, pack_tmp_name);
 593        }
 594
 595        if (do_progress)
 596                start_progress(&progress_state, "Writing %u objects...", "", nr_result);
 597
 598        hdr.hdr_signature = htonl(PACK_SIGNATURE);
 599        hdr.hdr_version = htonl(PACK_VERSION);
 600        hdr.hdr_entries = htonl(nr_result);
 601        sha1write(f, &hdr, sizeof(hdr));
 602        offset = sizeof(hdr);
 603        if (!nr_result)
 604                goto done;
 605        for (i = 0; i < nr_objects; i++) {
 606                last_obj_offset = offset;
 607                offset = write_one(f, objects + i, offset);
 608                if (do_progress)
 609                        display_progress(&progress_state, written);
 610        }
 611        if (do_progress)
 612                stop_progress(&progress_state);
 613 done:
 614        if (written != nr_result)
 615                die("wrote %u objects while expecting %u", written, nr_result);
 616        sha1close(f, pack_file_sha1, 1);
 617
 618        return last_obj_offset;
 619}
 620
 621static int sha1_sort(const void *_a, const void *_b)
 622{
 623        const struct object_entry *a = *(struct object_entry **)_a;
 624        const struct object_entry *b = *(struct object_entry **)_b;
 625        return hashcmp(a->sha1, b->sha1);
 626}
 627
 628static uint32_t index_default_version = 1;
 629static uint32_t index_off32_limit = 0x7fffffff;
 630
 631static void write_index_file(off_t last_obj_offset, unsigned char *sha1)
 632{
 633        struct sha1file *f;
 634        struct object_entry **sorted_by_sha, **list, **last;
 635        uint32_t array[256];
 636        uint32_t i, index_version;
 637        SHA_CTX ctx;
 638
 639        int fd = open_object_dir_tmp("tmp_idx_XXXXXX");
 640        if (fd < 0)
 641                die("unable to create %s: %s\n", tmpname, strerror(errno));
 642        idx_tmp_name = xstrdup(tmpname);
 643        f = sha1fd(fd, idx_tmp_name);
 644
 645        if (nr_result) {
 646                uint32_t j = 0;
 647                sorted_by_sha =
 648                        xcalloc(nr_result, sizeof(struct object_entry *));
 649                for (i = 0; i < nr_objects; i++)
 650                        if (!objects[i].preferred_base)
 651                                sorted_by_sha[j++] = objects + i;
 652                if (j != nr_result)
 653                        die("listed %u objects while expecting %u", j, nr_result);
 654                qsort(sorted_by_sha, nr_result, sizeof(*sorted_by_sha), sha1_sort);
 655                list = sorted_by_sha;
 656                last = sorted_by_sha + nr_result;
 657        } else
 658                sorted_by_sha = list = last = NULL;
 659
 660        /* if last object's offset is >= 2^31 we should use index V2 */
 661        index_version = (last_obj_offset >> 31) ? 2 : index_default_version;
 662
 663        /* index versions 2 and above need a header */
 664        if (index_version >= 2) {
 665                struct pack_idx_header hdr;
 666                hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
 667                hdr.idx_version = htonl(index_version);
 668                sha1write(f, &hdr, sizeof(hdr));
 669        }
 670
 671        /*
 672         * Write the first-level table (the list is sorted,
 673         * but we use a 256-entry lookup to be able to avoid
 674         * having to do eight extra binary search iterations).
 675         */
 676        for (i = 0; i < 256; i++) {
 677                struct object_entry **next = list;
 678                while (next < last) {
 679                        struct object_entry *entry = *next;
 680                        if (entry->sha1[0] != i)
 681                                break;
 682                        next++;
 683                }
 684                array[i] = htonl(next - sorted_by_sha);
 685                list = next;
 686        }
 687        sha1write(f, array, 256 * 4);
 688
 689        /* Compute the SHA1 hash of sorted object names. */
 690        SHA1_Init(&ctx);
 691
 692        /* Write the actual SHA1 entries. */
 693        list = sorted_by_sha;
 694        for (i = 0; i < nr_result; i++) {
 695                struct object_entry *entry = *list++;
 696                if (index_version < 2) {
 697                        uint32_t offset = htonl(entry->offset);
 698                        sha1write(f, &offset, 4);
 699                }
 700                sha1write(f, entry->sha1, 20);
 701                SHA1_Update(&ctx, entry->sha1, 20);
 702        }
 703
 704        if (index_version >= 2) {
 705                unsigned int nr_large_offset = 0;
 706
 707                /* write the crc32 table */
 708                list = sorted_by_sha;
 709                for (i = 0; i < nr_objects; i++) {
 710                        struct object_entry *entry = *list++;
 711                        uint32_t crc32_val = htonl(entry->crc32);
 712                        sha1write(f, &crc32_val, 4);
 713                }
 714
 715                /* write the 32-bit offset table */
 716                list = sorted_by_sha;
 717                for (i = 0; i < nr_objects; i++) {
 718                        struct object_entry *entry = *list++;
 719                        uint32_t offset = (entry->offset <= index_off32_limit) ?
 720                                entry->offset : (0x80000000 | nr_large_offset++);
 721                        offset = htonl(offset);
 722                        sha1write(f, &offset, 4);
 723                }
 724
 725                /* write the large offset table */
 726                list = sorted_by_sha;
 727                while (nr_large_offset) {
 728                        struct object_entry *entry = *list++;
 729                        uint64_t offset = entry->offset;
 730                        if (offset > index_off32_limit) {
 731                                uint32_t split[2];
 732                                split[0]        = htonl(offset >> 32);
 733                                split[1] = htonl(offset & 0xffffffff);
 734                                sha1write(f, split, 8);
 735                                nr_large_offset--;
 736                        }
 737                }
 738        }
 739
 740        sha1write(f, pack_file_sha1, 20);
 741        sha1close(f, NULL, 1);
 742        free(sorted_by_sha);
 743        SHA1_Final(sha1, &ctx);
 744}
 745
 746static int locate_object_entry_hash(const unsigned char *sha1)
 747{
 748        int i;
 749        unsigned int ui;
 750        memcpy(&ui, sha1, sizeof(unsigned int));
 751        i = ui % object_ix_hashsz;
 752        while (0 < object_ix[i]) {
 753                if (!hashcmp(sha1, objects[object_ix[i] - 1].sha1))
 754                        return i;
 755                if (++i == object_ix_hashsz)
 756                        i = 0;
 757        }
 758        return -1 - i;
 759}
 760
 761static struct object_entry *locate_object_entry(const unsigned char *sha1)
 762{
 763        int i;
 764
 765        if (!object_ix_hashsz)
 766                return NULL;
 767
 768        i = locate_object_entry_hash(sha1);
 769        if (0 <= i)
 770                return &objects[object_ix[i]-1];
 771        return NULL;
 772}
 773
 774static void rehash_objects(void)
 775{
 776        uint32_t i;
 777        struct object_entry *oe;
 778
 779        object_ix_hashsz = nr_objects * 3;
 780        if (object_ix_hashsz < 1024)
 781                object_ix_hashsz = 1024;
 782        object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 783        memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 784        for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 785                int ix = locate_object_entry_hash(oe->sha1);
 786                if (0 <= ix)
 787                        continue;
 788                ix = -1 - ix;
 789                object_ix[ix] = i + 1;
 790        }
 791}
 792
 793static unsigned name_hash(const char *name)
 794{
 795        unsigned char c;
 796        unsigned hash = 0;
 797
 798        /*
 799         * This effectively just creates a sortable number from the
 800         * last sixteen non-whitespace characters. Last characters
 801         * count "most", so things that end in ".c" sort together.
 802         */
 803        while ((c = *name++) != 0) {
 804                if (isspace(c))
 805                        continue;
 806                hash = (hash >> 2) + (c << 24);
 807        }
 808        return hash;
 809}
 810
 811static int add_object_entry(const unsigned char *sha1, enum object_type type,
 812                            unsigned hash, int exclude)
 813{
 814        struct object_entry *entry;
 815        struct packed_git *p, *found_pack = NULL;
 816        off_t found_offset = 0;
 817        int ix;
 818
 819        ix = nr_objects ? locate_object_entry_hash(sha1) : -1;
 820        if (ix >= 0) {
 821                if (exclude) {
 822                        entry = objects + object_ix[ix] - 1;
 823                        if (!entry->preferred_base)
 824                                nr_result--;
 825                        entry->preferred_base = 1;
 826                }
 827                return 0;
 828        }
 829
 830        for (p = packed_git; p; p = p->next) {
 831                off_t offset = find_pack_entry_one(sha1, p);
 832                if (offset) {
 833                        if (!found_pack) {
 834                                found_offset = offset;
 835                                found_pack = p;
 836                        }
 837                        if (exclude)
 838                                break;
 839                        if (incremental)
 840                                return 0;
 841                        if (local && !p->pack_local)
 842                                return 0;
 843                }
 844        }
 845
 846        if (nr_objects >= nr_alloc) {
 847                nr_alloc = (nr_alloc  + 1024) * 3 / 2;
 848                objects = xrealloc(objects, nr_alloc * sizeof(*entry));
 849        }
 850
 851        entry = objects + nr_objects++;
 852        memset(entry, 0, sizeof(*entry));
 853        hashcpy(entry->sha1, sha1);
 854        entry->hash = hash;
 855        if (type)
 856                entry->type = type;
 857        if (exclude)
 858                entry->preferred_base = 1;
 859        else
 860                nr_result++;
 861        if (found_pack) {
 862                entry->in_pack = found_pack;
 863                entry->in_pack_offset = found_offset;
 864        }
 865
 866        if (object_ix_hashsz * 3 <= nr_objects * 4)
 867                rehash_objects();
 868        else
 869                object_ix[-1 - ix] = nr_objects;
 870
 871        if (progress)
 872                display_progress(&progress_state, nr_objects);
 873
 874        return 1;
 875}
 876
 877struct pbase_tree_cache {
 878        unsigned char sha1[20];
 879        int ref;
 880        int temporary;
 881        void *tree_data;
 882        unsigned long tree_size;
 883};
 884
 885static struct pbase_tree_cache *(pbase_tree_cache[256]);
 886static int pbase_tree_cache_ix(const unsigned char *sha1)
 887{
 888        return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 889}
 890static int pbase_tree_cache_ix_incr(int ix)
 891{
 892        return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 893}
 894
 895static struct pbase_tree {
 896        struct pbase_tree *next;
 897        /* This is a phony "cache" entry; we are not
 898         * going to evict it nor find it through _get()
 899         * mechanism -- this is for the toplevel node that
 900         * would almost always change with any commit.
 901         */
 902        struct pbase_tree_cache pcache;
 903} *pbase_tree;
 904
 905static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 906{
 907        struct pbase_tree_cache *ent, *nent;
 908        void *data;
 909        unsigned long size;
 910        enum object_type type;
 911        int neigh;
 912        int my_ix = pbase_tree_cache_ix(sha1);
 913        int available_ix = -1;
 914
 915        /* pbase-tree-cache acts as a limited hashtable.
 916         * your object will be found at your index or within a few
 917         * slots after that slot if it is cached.
 918         */
 919        for (neigh = 0; neigh < 8; neigh++) {
 920                ent = pbase_tree_cache[my_ix];
 921                if (ent && !hashcmp(ent->sha1, sha1)) {
 922                        ent->ref++;
 923                        return ent;
 924                }
 925                else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 926                         ((0 <= available_ix) &&
 927                          (!ent && pbase_tree_cache[available_ix])))
 928                        available_ix = my_ix;
 929                if (!ent)
 930                        break;
 931                my_ix = pbase_tree_cache_ix_incr(my_ix);
 932        }
 933
 934        /* Did not find one.  Either we got a bogus request or
 935         * we need to read and perhaps cache.
 936         */
 937        data = read_sha1_file(sha1, &type, &size);
 938        if (!data)
 939                return NULL;
 940        if (type != OBJ_TREE) {
 941                free(data);
 942                return NULL;
 943        }
 944
 945        /* We need to either cache or return a throwaway copy */
 946
 947        if (available_ix < 0)
 948                ent = NULL;
 949        else {
 950                ent = pbase_tree_cache[available_ix];
 951                my_ix = available_ix;
 952        }
 953
 954        if (!ent) {
 955                nent = xmalloc(sizeof(*nent));
 956                nent->temporary = (available_ix < 0);
 957        }
 958        else {
 959                /* evict and reuse */
 960                free(ent->tree_data);
 961                nent = ent;
 962        }
 963        hashcpy(nent->sha1, sha1);
 964        nent->tree_data = data;
 965        nent->tree_size = size;
 966        nent->ref = 1;
 967        if (!nent->temporary)
 968                pbase_tree_cache[my_ix] = nent;
 969        return nent;
 970}
 971
 972static void pbase_tree_put(struct pbase_tree_cache *cache)
 973{
 974        if (!cache->temporary) {
 975                cache->ref--;
 976                return;
 977        }
 978        free(cache->tree_data);
 979        free(cache);
 980}
 981
 982static int name_cmp_len(const char *name)
 983{
 984        int i;
 985        for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 986                ;
 987        return i;
 988}
 989
 990static void add_pbase_object(struct tree_desc *tree,
 991                             const char *name,
 992                             int cmplen,
 993                             const char *fullname)
 994{
 995        struct name_entry entry;
 996        int cmp;
 997
 998        while (tree_entry(tree,&entry)) {
 999                cmp = tree_entry_len(entry.path, entry.sha1) != cmplen ? 1 :
1000                      memcmp(name, entry.path, cmplen);
1001                if (cmp > 0)
1002                        continue;
1003                if (cmp < 0)
1004                        return;
1005                if (name[cmplen] != '/') {
1006                        unsigned hash = name_hash(fullname);
1007                        add_object_entry(entry.sha1,
1008                                         S_ISDIR(entry.mode) ? OBJ_TREE : OBJ_BLOB,
1009                                         hash, 1);
1010                        return;
1011                }
1012                if (S_ISDIR(entry.mode)) {
1013                        struct tree_desc sub;
1014                        struct pbase_tree_cache *tree;
1015                        const char *down = name+cmplen+1;
1016                        int downlen = name_cmp_len(down);
1017
1018                        tree = pbase_tree_get(entry.sha1);
1019                        if (!tree)
1020                                return;
1021                        init_tree_desc(&sub, tree->tree_data, tree->tree_size);
1022
1023                        add_pbase_object(&sub, down, downlen, fullname);
1024                        pbase_tree_put(tree);
1025                }
1026        }
1027}
1028
1029static unsigned *done_pbase_paths;
1030static int done_pbase_paths_num;
1031static int done_pbase_paths_alloc;
1032static int done_pbase_path_pos(unsigned hash)
1033{
1034        int lo = 0;
1035        int hi = done_pbase_paths_num;
1036        while (lo < hi) {
1037                int mi = (hi + lo) / 2;
1038                if (done_pbase_paths[mi] == hash)
1039                        return mi;
1040                if (done_pbase_paths[mi] < hash)
1041                        hi = mi;
1042                else
1043                        lo = mi + 1;
1044        }
1045        return -lo-1;
1046}
1047
1048static int check_pbase_path(unsigned hash)
1049{
1050        int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
1051        if (0 <= pos)
1052                return 1;
1053        pos = -pos - 1;
1054        if (done_pbase_paths_alloc <= done_pbase_paths_num) {
1055                done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
1056                done_pbase_paths = xrealloc(done_pbase_paths,
1057                                            done_pbase_paths_alloc *
1058                                            sizeof(unsigned));
1059        }
1060        done_pbase_paths_num++;
1061        if (pos < done_pbase_paths_num)
1062                memmove(done_pbase_paths + pos + 1,
1063                        done_pbase_paths + pos,
1064                        (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
1065        done_pbase_paths[pos] = hash;
1066        return 0;
1067}
1068
1069static void add_preferred_base_object(const char *name, unsigned hash)
1070{
1071        struct pbase_tree *it;
1072        int cmplen;
1073
1074        if (!num_preferred_base || check_pbase_path(hash))
1075                return;
1076
1077        cmplen = name_cmp_len(name);
1078        for (it = pbase_tree; it; it = it->next) {
1079                if (cmplen == 0) {
1080                        add_object_entry(it->pcache.sha1, OBJ_TREE, 0, 1);
1081                }
1082                else {
1083                        struct tree_desc tree;
1084                        init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
1085                        add_pbase_object(&tree, name, cmplen, name);
1086                }
1087        }
1088}
1089
1090static void add_preferred_base(unsigned char *sha1)
1091{
1092        struct pbase_tree *it;
1093        void *data;
1094        unsigned long size;
1095        unsigned char tree_sha1[20];
1096
1097        if (window <= num_preferred_base++)
1098                return;
1099
1100        data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
1101        if (!data)
1102                return;
1103
1104        for (it = pbase_tree; it; it = it->next) {
1105                if (!hashcmp(it->pcache.sha1, tree_sha1)) {
1106                        free(data);
1107                        return;
1108                }
1109        }
1110
1111        it = xcalloc(1, sizeof(*it));
1112        it->next = pbase_tree;
1113        pbase_tree = it;
1114
1115        hashcpy(it->pcache.sha1, tree_sha1);
1116        it->pcache.tree_data = data;
1117        it->pcache.tree_size = size;
1118}
1119
1120static void check_object(struct object_entry *entry)
1121{
1122        if (entry->in_pack) {
1123                struct packed_git *p = entry->in_pack;
1124                struct pack_window *w_curs = NULL;
1125                const unsigned char *base_ref = NULL;
1126                struct object_entry *base_entry;
1127                unsigned long used, used_0;
1128                unsigned int avail;
1129                off_t ofs;
1130                unsigned char *buf, c;
1131
1132                buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
1133
1134                /*
1135                 * We want in_pack_type even if we do not reuse delta
1136                 * since non-delta representations could still be reused.
1137                 */
1138                used = unpack_object_header_gently(buf, avail,
1139                                                   &entry->in_pack_type,
1140                                                   &entry->size);
1141
1142                /*
1143                 * Determine if this is a delta and if so whether we can
1144                 * reuse it or not.  Otherwise let's find out as cheaply as
1145                 * possible what the actual type and size for this object is.
1146                 */
1147                switch (entry->in_pack_type) {
1148                default:
1149                        /* Not a delta hence we've already got all we need. */
1150                        entry->type = entry->in_pack_type;
1151                        entry->in_pack_header_size = used;
1152                        unuse_pack(&w_curs);
1153                        return;
1154                case OBJ_REF_DELTA:
1155                        if (!no_reuse_delta && !entry->preferred_base)
1156                                base_ref = use_pack(p, &w_curs,
1157                                                entry->in_pack_offset + used, NULL);
1158                        entry->in_pack_header_size = used + 20;
1159                        break;
1160                case OBJ_OFS_DELTA:
1161                        buf = use_pack(p, &w_curs,
1162                                       entry->in_pack_offset + used, NULL);
1163                        used_0 = 0;
1164                        c = buf[used_0++];
1165                        ofs = c & 127;
1166                        while (c & 128) {
1167                                ofs += 1;
1168                                if (!ofs || MSB(ofs, 7))
1169                                        die("delta base offset overflow in pack for %s",
1170                                            sha1_to_hex(entry->sha1));
1171                                c = buf[used_0++];
1172                                ofs = (ofs << 7) + (c & 127);
1173                        }
1174                        if (ofs >= entry->in_pack_offset)
1175                                die("delta base offset out of bound for %s",
1176                                    sha1_to_hex(entry->sha1));
1177                        ofs = entry->in_pack_offset - ofs;
1178                        if (!no_reuse_delta && !entry->preferred_base)
1179                                base_ref = find_packed_object_name(p, ofs);
1180                        entry->in_pack_header_size = used + used_0;
1181                        break;
1182                }
1183
1184                if (base_ref && (base_entry = locate_object_entry(base_ref))) {
1185                        /*
1186                         * If base_ref was set above that means we wish to
1187                         * reuse delta data, and we even found that base
1188                         * in the list of objects we want to pack. Goodie!
1189                         *
1190                         * Depth value does not matter - find_deltas() will
1191                         * never consider reused delta as the base object to
1192                         * deltify other objects against, in order to avoid
1193                         * circular deltas.
1194                         */
1195                        entry->type = entry->in_pack_type;
1196                        entry->delta = base_entry;
1197                        entry->delta_sibling = base_entry->delta_child;
1198                        base_entry->delta_child = entry;
1199                        unuse_pack(&w_curs);
1200                        return;
1201                }
1202
1203                if (entry->type) {
1204                        /*
1205                         * This must be a delta and we already know what the
1206                         * final object type is.  Let's extract the actual
1207                         * object size from the delta header.
1208                         */
1209                        entry->size = get_size_from_delta(p, &w_curs,
1210                                        entry->in_pack_offset + entry->in_pack_header_size);
1211                        unuse_pack(&w_curs);
1212                        return;
1213                }
1214
1215                /*
1216                 * No choice but to fall back to the recursive delta walk
1217                 * with sha1_object_info() to find about the object type
1218                 * at this point...
1219                 */
1220                unuse_pack(&w_curs);
1221        }
1222
1223        entry->type = sha1_object_info(entry->sha1, &entry->size);
1224        if (entry->type < 0)
1225                die("unable to get type of object %s",
1226                    sha1_to_hex(entry->sha1));
1227}
1228
1229static int pack_offset_sort(const void *_a, const void *_b)
1230{
1231        const struct object_entry *a = *(struct object_entry **)_a;
1232        const struct object_entry *b = *(struct object_entry **)_b;
1233
1234        /* avoid filesystem trashing with loose objects */
1235        if (!a->in_pack && !b->in_pack)
1236                return hashcmp(a->sha1, b->sha1);
1237
1238        if (a->in_pack < b->in_pack)
1239                return -1;
1240        if (a->in_pack > b->in_pack)
1241                return 1;
1242        return a->in_pack_offset < b->in_pack_offset ? -1 :
1243                        (a->in_pack_offset > b->in_pack_offset);
1244}
1245
1246static void get_object_details(void)
1247{
1248        uint32_t i;
1249        struct object_entry **sorted_by_offset;
1250
1251        sorted_by_offset = xcalloc(nr_objects, sizeof(struct object_entry *));
1252        for (i = 0; i < nr_objects; i++)
1253                sorted_by_offset[i] = objects + i;
1254        qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
1255
1256        prepare_pack_ix();
1257        for (i = 0; i < nr_objects; i++)
1258                check_object(sorted_by_offset[i]);
1259        free(sorted_by_offset);
1260}
1261
1262static int type_size_sort(const void *_a, const void *_b)
1263{
1264        const struct object_entry *a = *(struct object_entry **)_a;
1265        const struct object_entry *b = *(struct object_entry **)_b;
1266
1267        if (a->type < b->type)
1268                return -1;
1269        if (a->type > b->type)
1270                return 1;
1271        if (a->hash < b->hash)
1272                return -1;
1273        if (a->hash > b->hash)
1274                return 1;
1275        if (a->preferred_base < b->preferred_base)
1276                return -1;
1277        if (a->preferred_base > b->preferred_base)
1278                return 1;
1279        if (a->size < b->size)
1280                return -1;
1281        if (a->size > b->size)
1282                return 1;
1283        return a > b ? -1 : (a < b);  /* newest last */
1284}
1285
1286struct unpacked {
1287        struct object_entry *entry;
1288        void *data;
1289        struct delta_index *index;
1290};
1291
1292/*
1293 * We search for deltas _backwards_ in a list sorted by type and
1294 * by size, so that we see progressively smaller and smaller files.
1295 * That's because we prefer deltas to be from the bigger file
1296 * to the smaller - deletes are potentially cheaper, but perhaps
1297 * more importantly, the bigger file is likely the more recent
1298 * one.
1299 */
1300static int try_delta(struct unpacked *trg, struct unpacked *src,
1301                     unsigned max_depth)
1302{
1303        struct object_entry *trg_entry = trg->entry;
1304        struct object_entry *src_entry = src->entry;
1305        unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
1306        enum object_type type;
1307        void *delta_buf;
1308
1309        /* Don't bother doing diffs between different types */
1310        if (trg_entry->type != src_entry->type)
1311                return -1;
1312
1313        /* We do not compute delta to *create* objects we are not
1314         * going to pack.
1315         */
1316        if (trg_entry->preferred_base)
1317                return -1;
1318
1319        /*
1320         * We do not bother to try a delta that we discarded
1321         * on an earlier try, but only when reusing delta data.
1322         */
1323        if (!no_reuse_delta && trg_entry->in_pack &&
1324            trg_entry->in_pack == src_entry->in_pack &&
1325            trg_entry->in_pack_type != OBJ_REF_DELTA &&
1326            trg_entry->in_pack_type != OBJ_OFS_DELTA)
1327                return 0;
1328
1329        /* Let's not bust the allowed depth. */
1330        if (src_entry->depth >= max_depth)
1331                return 0;
1332
1333        /* Now some size filtering heuristics. */
1334        trg_size = trg_entry->size;
1335        max_size = trg_size/2 - 20;
1336        max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1337        if (max_size == 0)
1338                return 0;
1339        if (trg_entry->delta && trg_entry->delta_size <= max_size)
1340                max_size = trg_entry->delta_size-1;
1341        src_size = src_entry->size;
1342        sizediff = src_size < trg_size ? trg_size - src_size : 0;
1343        if (sizediff >= max_size)
1344                return 0;
1345
1346        /* Load data if not already done */
1347        if (!trg->data) {
1348                trg->data = read_sha1_file(trg_entry->sha1, &type, &sz);
1349                if (sz != trg_size)
1350                        die("object %s inconsistent object length (%lu vs %lu)",
1351                            sha1_to_hex(trg_entry->sha1), sz, trg_size);
1352        }
1353        if (!src->data) {
1354                src->data = read_sha1_file(src_entry->sha1, &type, &sz);
1355                if (sz != src_size)
1356                        die("object %s inconsistent object length (%lu vs %lu)",
1357                            sha1_to_hex(src_entry->sha1), sz, src_size);
1358        }
1359        if (!src->index) {
1360                src->index = create_delta_index(src->data, src_size);
1361                if (!src->index)
1362                        die("out of memory");
1363        }
1364
1365        delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1366        if (!delta_buf)
1367                return 0;
1368
1369        trg_entry->delta = src_entry;
1370        trg_entry->delta_size = delta_size;
1371        trg_entry->depth = src_entry->depth + 1;
1372        free(delta_buf);
1373        return 1;
1374}
1375
1376static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
1377{
1378        struct object_entry *child = me->delta_child;
1379        unsigned int m = n;
1380        while (child) {
1381                unsigned int c = check_delta_limit(child, n + 1);
1382                if (m < c)
1383                        m = c;
1384                child = child->delta_sibling;
1385        }
1386        return m;
1387}
1388
1389static void find_deltas(struct object_entry **list, int window, int depth)
1390{
1391        uint32_t i = nr_objects, idx = 0, processed = 0;
1392        unsigned int array_size = window * sizeof(struct unpacked);
1393        struct unpacked *array;
1394        int max_depth;
1395
1396        if (!nr_objects)
1397                return;
1398        array = xmalloc(array_size);
1399        memset(array, 0, array_size);
1400        if (progress)
1401                start_progress(&progress_state, "Deltifying %u objects...", "", nr_result);
1402
1403        do {
1404                struct object_entry *entry = list[--i];
1405                struct unpacked *n = array + idx;
1406                int j;
1407
1408                if (!entry->preferred_base)
1409                        processed++;
1410
1411                if (progress)
1412                        display_progress(&progress_state, processed);
1413
1414                if (entry->delta)
1415                        /* This happens if we decided to reuse existing
1416                         * delta from a pack.  "!no_reuse_delta &&" is implied.
1417                         */
1418                        continue;
1419
1420                if (entry->size < 50)
1421                        continue;
1422                free_delta_index(n->index);
1423                n->index = NULL;
1424                free(n->data);
1425                n->data = NULL;
1426                n->entry = entry;
1427
1428                /*
1429                 * If the current object is at pack edge, take the depth the
1430                 * objects that depend on the current object into account
1431                 * otherwise they would become too deep.
1432                 */
1433                max_depth = depth;
1434                if (entry->delta_child) {
1435                        max_depth -= check_delta_limit(entry, 0);
1436                        if (max_depth <= 0)
1437                                goto next;
1438                }
1439
1440                j = window;
1441                while (--j > 0) {
1442                        uint32_t other_idx = idx + j;
1443                        struct unpacked *m;
1444                        if (other_idx >= window)
1445                                other_idx -= window;
1446                        m = array + other_idx;
1447                        if (!m->entry)
1448                                break;
1449                        if (try_delta(n, m, max_depth) < 0)
1450                                break;
1451                }
1452
1453                /* if we made n a delta, and if n is already at max
1454                 * depth, leaving it in the window is pointless.  we
1455                 * should evict it first.
1456                 */
1457                if (entry->delta && depth <= entry->depth)
1458                        continue;
1459
1460                next:
1461                idx++;
1462                if (idx >= window)
1463                        idx = 0;
1464        } while (i > 0);
1465
1466        if (progress)
1467                stop_progress(&progress_state);
1468
1469        for (i = 0; i < window; ++i) {
1470                free_delta_index(array[i].index);
1471                free(array[i].data);
1472        }
1473        free(array);
1474}
1475
1476static void prepare_pack(int window, int depth)
1477{
1478        struct object_entry **delta_list;
1479        uint32_t i;
1480
1481        get_object_details();
1482
1483        if (!window || !depth)
1484                return;
1485
1486        delta_list = xmalloc(nr_objects * sizeof(*delta_list));
1487        for (i = 0; i < nr_objects; i++)
1488                delta_list[i] = objects + i;
1489        qsort(delta_list, nr_objects, sizeof(*delta_list), type_size_sort);
1490        find_deltas(delta_list, window+1, depth);
1491        free(delta_list);
1492}
1493
1494static int git_pack_config(const char *k, const char *v)
1495{
1496        if(!strcmp(k, "pack.window")) {
1497                window = git_config_int(k, v);
1498                return 0;
1499        }
1500        if(!strcmp(k, "pack.depth")) {
1501                depth = git_config_int(k, v);
1502                return 0;
1503        }
1504        if (!strcmp(k, "pack.compression")) {
1505                int level = git_config_int(k, v);
1506                if (level == -1)
1507                        level = Z_DEFAULT_COMPRESSION;
1508                else if (level < 0 || level > Z_BEST_COMPRESSION)
1509                        die("bad pack compression level %d", level);
1510                pack_compression_level = level;
1511                pack_compression_seen = 1;
1512                return 0;
1513        }
1514        return git_default_config(k, v);
1515}
1516
1517static void read_object_list_from_stdin(void)
1518{
1519        char line[40 + 1 + PATH_MAX + 2];
1520        unsigned char sha1[20];
1521        unsigned hash;
1522
1523        for (;;) {
1524                if (!fgets(line, sizeof(line), stdin)) {
1525                        if (feof(stdin))
1526                                break;
1527                        if (!ferror(stdin))
1528                                die("fgets returned NULL, not EOF, not error!");
1529                        if (errno != EINTR)
1530                                die("fgets: %s", strerror(errno));
1531                        clearerr(stdin);
1532                        continue;
1533                }
1534                if (line[0] == '-') {
1535                        if (get_sha1_hex(line+1, sha1))
1536                                die("expected edge sha1, got garbage:\n %s",
1537                                    line);
1538                        add_preferred_base(sha1);
1539                        continue;
1540                }
1541                if (get_sha1_hex(line, sha1))
1542                        die("expected sha1, got garbage:\n %s", line);
1543
1544                hash = name_hash(line+41);
1545                add_preferred_base_object(line+41, hash);
1546                add_object_entry(sha1, 0, hash, 0);
1547        }
1548}
1549
1550static void show_commit(struct commit *commit)
1551{
1552        add_object_entry(commit->object.sha1, OBJ_COMMIT, 0, 0);
1553}
1554
1555static void show_object(struct object_array_entry *p)
1556{
1557        unsigned hash = name_hash(p->name);
1558        add_preferred_base_object(p->name, hash);
1559        add_object_entry(p->item->sha1, p->item->type, hash, 0);
1560}
1561
1562static void show_edge(struct commit *commit)
1563{
1564        add_preferred_base(commit->object.sha1);
1565}
1566
1567static void get_object_list(int ac, const char **av)
1568{
1569        struct rev_info revs;
1570        char line[1000];
1571        int flags = 0;
1572
1573        init_revisions(&revs, NULL);
1574        save_commit_buffer = 0;
1575        track_object_refs = 0;
1576        setup_revisions(ac, av, &revs, NULL);
1577
1578        while (fgets(line, sizeof(line), stdin) != NULL) {
1579                int len = strlen(line);
1580                if (line[len - 1] == '\n')
1581                        line[--len] = 0;
1582                if (!len)
1583                        break;
1584                if (*line == '-') {
1585                        if (!strcmp(line, "--not")) {
1586                                flags ^= UNINTERESTING;
1587                                continue;
1588                        }
1589                        die("not a rev '%s'", line);
1590                }
1591                if (handle_revision_arg(line, &revs, flags, 1))
1592                        die("bad revision '%s'", line);
1593        }
1594
1595        prepare_revision_walk(&revs);
1596        mark_edges_uninteresting(revs.commits, &revs, show_edge);
1597        traverse_commit_list(&revs, show_commit, show_object);
1598}
1599
1600static int adjust_perm(const char *path, mode_t mode)
1601{
1602        if (chmod(path, mode))
1603                return -1;
1604        return adjust_shared_perm(path);
1605}
1606
1607int cmd_pack_objects(int argc, const char **argv, const char *prefix)
1608{
1609        int use_internal_rev_list = 0;
1610        int thin = 0;
1611        uint32_t i;
1612        off_t last_obj_offset;
1613        const char *base_name = NULL;
1614        const char **rp_av;
1615        int rp_ac_alloc = 64;
1616        int rp_ac;
1617
1618        rp_av = xcalloc(rp_ac_alloc, sizeof(*rp_av));
1619
1620        rp_av[0] = "pack-objects";
1621        rp_av[1] = "--objects"; /* --thin will make it --objects-edge */
1622        rp_ac = 2;
1623
1624        git_config(git_pack_config);
1625        if (!pack_compression_seen && core_compression_seen)
1626                pack_compression_level = core_compression_level;
1627
1628        progress = isatty(2);
1629        for (i = 1; i < argc; i++) {
1630                const char *arg = argv[i];
1631
1632                if (*arg != '-')
1633                        break;
1634
1635                if (!strcmp("--non-empty", arg)) {
1636                        non_empty = 1;
1637                        continue;
1638                }
1639                if (!strcmp("--local", arg)) {
1640                        local = 1;
1641                        continue;
1642                }
1643                if (!strcmp("--incremental", arg)) {
1644                        incremental = 1;
1645                        continue;
1646                }
1647                if (!prefixcmp(arg, "--compression=")) {
1648                        char *end;
1649                        int level = strtoul(arg+14, &end, 0);
1650                        if (!arg[14] || *end)
1651                                usage(pack_usage);
1652                        if (level == -1)
1653                                level = Z_DEFAULT_COMPRESSION;
1654                        else if (level < 0 || level > Z_BEST_COMPRESSION)
1655                                die("bad pack compression level %d", level);
1656                        pack_compression_level = level;
1657                        continue;
1658                }
1659                if (!prefixcmp(arg, "--window=")) {
1660                        char *end;
1661                        window = strtoul(arg+9, &end, 0);
1662                        if (!arg[9] || *end)
1663                                usage(pack_usage);
1664                        continue;
1665                }
1666                if (!prefixcmp(arg, "--depth=")) {
1667                        char *end;
1668                        depth = strtoul(arg+8, &end, 0);
1669                        if (!arg[8] || *end)
1670                                usage(pack_usage);
1671                        continue;
1672                }
1673                if (!strcmp("--progress", arg)) {
1674                        progress = 1;
1675                        continue;
1676                }
1677                if (!strcmp("--all-progress", arg)) {
1678                        progress = 2;
1679                        continue;
1680                }
1681                if (!strcmp("-q", arg)) {
1682                        progress = 0;
1683                        continue;
1684                }
1685                if (!strcmp("--no-reuse-delta", arg)) {
1686                        no_reuse_delta = 1;
1687                        continue;
1688                }
1689                if (!strcmp("--no-reuse-object", arg)) {
1690                        no_reuse_object = no_reuse_delta = 1;
1691                        continue;
1692                }
1693                if (!strcmp("--delta-base-offset", arg)) {
1694                        allow_ofs_delta = 1;
1695                        continue;
1696                }
1697                if (!strcmp("--stdout", arg)) {
1698                        pack_to_stdout = 1;
1699                        continue;
1700                }
1701                if (!strcmp("--revs", arg)) {
1702                        use_internal_rev_list = 1;
1703                        continue;
1704                }
1705                if (!strcmp("--unpacked", arg) ||
1706                    !prefixcmp(arg, "--unpacked=") ||
1707                    !strcmp("--reflog", arg) ||
1708                    !strcmp("--all", arg)) {
1709                        use_internal_rev_list = 1;
1710                        if (rp_ac >= rp_ac_alloc - 1) {
1711                                rp_ac_alloc = alloc_nr(rp_ac_alloc);
1712                                rp_av = xrealloc(rp_av,
1713                                                 rp_ac_alloc * sizeof(*rp_av));
1714                        }
1715                        rp_av[rp_ac++] = arg;
1716                        continue;
1717                }
1718                if (!strcmp("--thin", arg)) {
1719                        use_internal_rev_list = 1;
1720                        thin = 1;
1721                        rp_av[1] = "--objects-edge";
1722                        continue;
1723                }
1724                if (!prefixcmp(arg, "--index-version=")) {
1725                        char *c;
1726                        index_default_version = strtoul(arg + 16, &c, 10);
1727                        if (index_default_version > 2)
1728                                die("bad %s", arg);
1729                        if (*c == ',')
1730                                index_off32_limit = strtoul(c+1, &c, 0);
1731                        if (*c || index_off32_limit & 0x80000000)
1732                                die("bad %s", arg);
1733                        continue;
1734                }
1735                usage(pack_usage);
1736        }
1737
1738        /* Traditionally "pack-objects [options] base extra" failed;
1739         * we would however want to take refs parameter that would
1740         * have been given to upstream rev-list ourselves, which means
1741         * we somehow want to say what the base name is.  So the
1742         * syntax would be:
1743         *
1744         * pack-objects [options] base <refs...>
1745         *
1746         * in other words, we would treat the first non-option as the
1747         * base_name and send everything else to the internal revision
1748         * walker.
1749         */
1750
1751        if (!pack_to_stdout)
1752                base_name = argv[i++];
1753
1754        if (pack_to_stdout != !base_name)
1755                usage(pack_usage);
1756
1757        if (!pack_to_stdout && thin)
1758                die("--thin cannot be used to build an indexable pack.");
1759
1760        prepare_packed_git();
1761
1762        if (progress)
1763                start_progress(&progress_state, "Generating pack...",
1764                               "Counting objects: ", 0);
1765        if (!use_internal_rev_list)
1766                read_object_list_from_stdin();
1767        else {
1768                rp_av[rp_ac] = NULL;
1769                get_object_list(rp_ac, rp_av);
1770        }
1771        if (progress) {
1772                stop_progress(&progress_state);
1773                fprintf(stderr, "Done counting %u objects.\n", nr_objects);
1774        }
1775
1776        if (non_empty && !nr_result)
1777                return 0;
1778        if (progress && (nr_objects != nr_result))
1779                fprintf(stderr, "Result has %u objects.\n", nr_result);
1780        if (nr_result)
1781                prepare_pack(window, depth);
1782        last_obj_offset = write_pack_file();
1783        if (!pack_to_stdout) {
1784                unsigned char object_list_sha1[20];
1785                mode_t mode = umask(0);
1786
1787                umask(mode);
1788                mode = 0444 & ~mode;
1789
1790                write_index_file(last_obj_offset, object_list_sha1);
1791                snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
1792                         base_name, sha1_to_hex(object_list_sha1));
1793                if (adjust_perm(pack_tmp_name, mode))
1794                        die("unable to make temporary pack file readable: %s",
1795                            strerror(errno));
1796                if (rename(pack_tmp_name, tmpname))
1797                        die("unable to rename temporary pack file: %s",
1798                            strerror(errno));
1799                snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
1800                         base_name, sha1_to_hex(object_list_sha1));
1801                if (adjust_perm(idx_tmp_name, mode))
1802                        die("unable to make temporary index file readable: %s",
1803                            strerror(errno));
1804                if (rename(idx_tmp_name, tmpname))
1805                        die("unable to rename temporary index file: %s",
1806                            strerror(errno));
1807                puts(sha1_to_hex(object_list_sha1));
1808        }
1809        if (progress)
1810                fprintf(stderr, "Total %u (delta %u), reused %u (delta %u)\n",
1811                        written, written_delta, reused, reused_delta);
1812        return 0;
1813}