builtin-pack-objects.con commit diff -M: release the preimage candidate blobs after rename detection. (50b2b53)
   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] [--delta-base-offset] [--non-empty] \n\
  21        [--revs [--unpacked | --all]*] [--reflog] [--stdout | base-name] \n\
  22        [<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;
  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 pack_to_stdout;
  68static int num_preferred_base;
  69static struct progress progress_state;
  70
  71/*
  72 * The object names in objects array are hashed with this hashtable,
  73 * to help looking up the entry by object name.
  74 * This hashtable is built after all the objects are seen.
  75 */
  76static int *object_ix;
  77static int object_ix_hashsz;
  78
  79/*
  80 * Pack index for existing packs give us easy access to the offsets into
  81 * corresponding pack file where each object's data starts, but the entries
  82 * do not store the size of the compressed representation (uncompressed
  83 * size is easily available by examining the pack entry header).  It is
  84 * also rather expensive to find the sha1 for an object given its offset.
  85 *
  86 * We build a hashtable of existing packs (pack_revindex), and keep reverse
  87 * index here -- pack index file is sorted by object name mapping to offset;
  88 * this pack_revindex[].revindex array is a list of offset/index_nr pairs
  89 * ordered by offset, so if you know the offset of an object, next offset
  90 * is where its packed representation ends and the index_nr can be used to
  91 * get the object sha1 from the main index.
  92 */
  93struct revindex_entry {
  94        off_t offset;
  95        unsigned int nr;
  96};
  97struct pack_revindex {
  98        struct packed_git *p;
  99        struct revindex_entry *revindex;
 100};
 101static struct  pack_revindex *pack_revindex;
 102static int pack_revindex_hashsz;
 103
 104/*
 105 * stats
 106 */
 107static uint32_t written, written_delta;
 108static uint32_t reused, reused_delta;
 109
 110static int pack_revindex_ix(struct packed_git *p)
 111{
 112        unsigned long ui = (unsigned long)p;
 113        int i;
 114
 115        ui = ui ^ (ui >> 16); /* defeat structure alignment */
 116        i = (int)(ui % pack_revindex_hashsz);
 117        while (pack_revindex[i].p) {
 118                if (pack_revindex[i].p == p)
 119                        return i;
 120                if (++i == pack_revindex_hashsz)
 121                        i = 0;
 122        }
 123        return -1 - i;
 124}
 125
 126static void prepare_pack_ix(void)
 127{
 128        int num;
 129        struct packed_git *p;
 130        for (num = 0, p = packed_git; p; p = p->next)
 131                num++;
 132        if (!num)
 133                return;
 134        pack_revindex_hashsz = num * 11;
 135        pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 136        for (p = packed_git; p; p = p->next) {
 137                num = pack_revindex_ix(p);
 138                num = - 1 - num;
 139                pack_revindex[num].p = p;
 140        }
 141        /* revindex elements are lazily initialized */
 142}
 143
 144static int cmp_offset(const void *a_, const void *b_)
 145{
 146        const struct revindex_entry *a = a_;
 147        const struct revindex_entry *b = b_;
 148        return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
 149}
 150
 151/*
 152 * Ordered list of offsets of objects in the pack.
 153 */
 154static void prepare_pack_revindex(struct pack_revindex *rix)
 155{
 156        struct packed_git *p = rix->p;
 157        int num_ent = p->num_objects;
 158        int i;
 159        const char *index = p->index_data;
 160
 161        rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
 162        index += 4 * 256;
 163
 164        if (p->index_version > 1) {
 165                const uint32_t *off_32 =
 166                        (uint32_t *)(index + 8 + p->num_objects * (20 + 4));
 167                const uint32_t *off_64 = off_32 + p->num_objects;
 168                for (i = 0; i < num_ent; i++) {
 169                        uint32_t off = ntohl(*off_32++);
 170                        if (!(off & 0x80000000)) {
 171                                rix->revindex[i].offset = off;
 172                        } else {
 173                                rix->revindex[i].offset =
 174                                        ((uint64_t)ntohl(*off_64++)) << 32;
 175                                rix->revindex[i].offset |=
 176                                        ntohl(*off_64++);
 177                        }
 178                        rix->revindex[i].nr = i;
 179                }
 180        } else {
 181                for (i = 0; i < num_ent; i++) {
 182                        uint32_t hl = *((uint32_t *)(index + 24 * i));
 183                        rix->revindex[i].offset = ntohl(hl);
 184                        rix->revindex[i].nr = i;
 185                }
 186        }
 187
 188        /* This knows the pack format -- the 20-byte trailer
 189         * follows immediately after the last object data.
 190         */
 191        rix->revindex[num_ent].offset = p->pack_size - 20;
 192        rix->revindex[num_ent].nr = -1;
 193        qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
 194}
 195
 196static struct revindex_entry * find_packed_object(struct packed_git *p,
 197                                                  off_t ofs)
 198{
 199        int num;
 200        int lo, hi;
 201        struct pack_revindex *rix;
 202        struct revindex_entry *revindex;
 203        num = pack_revindex_ix(p);
 204        if (num < 0)
 205                die("internal error: pack revindex uninitialized");
 206        rix = &pack_revindex[num];
 207        if (!rix->revindex)
 208                prepare_pack_revindex(rix);
 209        revindex = rix->revindex;
 210        lo = 0;
 211        hi = p->num_objects + 1;
 212        do {
 213                int mi = (lo + hi) / 2;
 214                if (revindex[mi].offset == ofs) {
 215                        return revindex + mi;
 216                }
 217                else if (ofs < revindex[mi].offset)
 218                        hi = mi;
 219                else
 220                        lo = mi + 1;
 221        } while (lo < hi);
 222        die("internal error: pack revindex corrupt");
 223}
 224
 225static const unsigned char *find_packed_object_name(struct packed_git *p,
 226                                                    off_t ofs)
 227{
 228        struct revindex_entry *entry = find_packed_object(p, ofs);
 229        return nth_packed_object_sha1(p, entry->nr);
 230}
 231
 232static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 233{
 234        unsigned long othersize, delta_size;
 235        enum object_type type;
 236        void *otherbuf = read_sha1_file(entry->delta->sha1, &type, &othersize);
 237        void *delta_buf;
 238
 239        if (!otherbuf)
 240                die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 241        delta_buf = diff_delta(otherbuf, othersize,
 242                               buf, size, &delta_size, 0);
 243        if (!delta_buf || delta_size != entry->delta_size)
 244                die("delta size changed");
 245        free(buf);
 246        free(otherbuf);
 247        return delta_buf;
 248}
 249
 250/*
 251 * The per-object header is a pretty dense thing, which is
 252 *  - first byte: low four bits are "size", then three bits of "type",
 253 *    and the high bit is "size continues".
 254 *  - each byte afterwards: low seven bits are size continuation,
 255 *    with the high bit being "size continues"
 256 */
 257static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 258{
 259        int n = 1;
 260        unsigned char c;
 261
 262        if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
 263                die("bad type %d", type);
 264
 265        c = (type << 4) | (size & 15);
 266        size >>= 4;
 267        while (size) {
 268                *hdr++ = c | 0x80;
 269                c = size & 0x7f;
 270                size >>= 7;
 271                n++;
 272        }
 273        *hdr = c;
 274        return n;
 275}
 276
 277/*
 278 * we are going to reuse the existing object data as is.  make
 279 * sure it is not corrupt.
 280 */
 281static int check_pack_inflate(struct packed_git *p,
 282                struct pack_window **w_curs,
 283                off_t offset,
 284                off_t len,
 285                unsigned long expect)
 286{
 287        z_stream stream;
 288        unsigned char fakebuf[4096], *in;
 289        int st;
 290
 291        memset(&stream, 0, sizeof(stream));
 292        inflateInit(&stream);
 293        do {
 294                in = use_pack(p, w_curs, offset, &stream.avail_in);
 295                stream.next_in = in;
 296                stream.next_out = fakebuf;
 297                stream.avail_out = sizeof(fakebuf);
 298                st = inflate(&stream, Z_FINISH);
 299                offset += stream.next_in - in;
 300        } while (st == Z_OK || st == Z_BUF_ERROR);
 301        inflateEnd(&stream);
 302        return (st == Z_STREAM_END &&
 303                stream.total_out == expect &&
 304                stream.total_in == len) ? 0 : -1;
 305}
 306
 307static int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
 308                          off_t offset, off_t len, unsigned int nr)
 309{
 310        const uint32_t *index_crc;
 311        uint32_t data_crc = crc32(0, Z_NULL, 0);
 312
 313        do {
 314                unsigned int avail;
 315                void *data = use_pack(p, w_curs, offset, &avail);
 316                if (avail > len)
 317                        avail = len;
 318                data_crc = crc32(data_crc, data, avail);
 319                offset += avail;
 320                len -= avail;
 321        } while (len);
 322
 323        index_crc = p->index_data;
 324        index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
 325
 326        return data_crc != ntohl(*index_crc);
 327}
 328
 329static void copy_pack_data(struct sha1file *f,
 330                struct packed_git *p,
 331                struct pack_window **w_curs,
 332                off_t offset,
 333                off_t len)
 334{
 335        unsigned char *in;
 336        unsigned int avail;
 337
 338        while (len) {
 339                in = use_pack(p, w_curs, offset, &avail);
 340                if (avail > len)
 341                        avail = (unsigned int)len;
 342                sha1write(f, in, avail);
 343                offset += avail;
 344                len -= avail;
 345        }
 346}
 347
 348static int check_loose_inflate(unsigned char *data, unsigned long len, unsigned long expect)
 349{
 350        z_stream stream;
 351        unsigned char fakebuf[4096];
 352        int st;
 353
 354        memset(&stream, 0, sizeof(stream));
 355        stream.next_in = data;
 356        stream.avail_in = len;
 357        stream.next_out = fakebuf;
 358        stream.avail_out = sizeof(fakebuf);
 359        inflateInit(&stream);
 360
 361        while (1) {
 362                st = inflate(&stream, Z_FINISH);
 363                if (st == Z_STREAM_END || st == Z_OK) {
 364                        st = (stream.total_out == expect &&
 365                              stream.total_in == len) ? 0 : -1;
 366                        break;
 367                }
 368                if (st != Z_BUF_ERROR) {
 369                        st = -1;
 370                        break;
 371                }
 372                stream.next_out = fakebuf;
 373                stream.avail_out = sizeof(fakebuf);
 374        }
 375        inflateEnd(&stream);
 376        return st;
 377}
 378
 379static int revalidate_loose_object(struct object_entry *entry,
 380                                   unsigned char *map,
 381                                   unsigned long mapsize)
 382{
 383        /* we already know this is a loose object with new type header. */
 384        enum object_type type;
 385        unsigned long size, used;
 386
 387        if (pack_to_stdout)
 388                return 0;
 389
 390        used = unpack_object_header_gently(map, mapsize, &type, &size);
 391        if (!used)
 392                return -1;
 393        map += used;
 394        mapsize -= used;
 395        return check_loose_inflate(map, mapsize, size);
 396}
 397
 398static unsigned long write_object(struct sha1file *f,
 399                                  struct object_entry *entry)
 400{
 401        unsigned long size;
 402        enum object_type type;
 403        void *buf;
 404        unsigned char header[10];
 405        unsigned hdrlen;
 406        off_t datalen;
 407        enum object_type obj_type;
 408        int to_reuse = 0;
 409
 410        if (!pack_to_stdout)
 411                crc32_begin(f);
 412
 413        obj_type = entry->type;
 414        if (! entry->in_pack)
 415                to_reuse = 0;   /* can't reuse what we don't have */
 416        else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
 417                to_reuse = 1;   /* check_object() decided it for us */
 418        else if (obj_type != entry->in_pack_type)
 419                to_reuse = 0;   /* pack has delta which is unusable */
 420        else if (entry->delta)
 421                to_reuse = 0;   /* we want to pack afresh */
 422        else
 423                to_reuse = 1;   /* we have it in-pack undeltified,
 424                                 * and we do not need to deltify it.
 425                                 */
 426
 427        if (!entry->in_pack && !entry->delta) {
 428                unsigned char *map;
 429                unsigned long mapsize;
 430                map = map_sha1_file(entry->sha1, &mapsize);
 431                if (map && !legacy_loose_object(map)) {
 432                        /* We can copy straight into the pack file */
 433                        if (revalidate_loose_object(entry, map, mapsize))
 434                                die("corrupt loose object %s",
 435                                    sha1_to_hex(entry->sha1));
 436                        sha1write(f, map, mapsize);
 437                        munmap(map, mapsize);
 438                        written++;
 439                        reused++;
 440                        return mapsize;
 441                }
 442                if (map)
 443                        munmap(map, mapsize);
 444        }
 445
 446        if (!to_reuse) {
 447                buf = read_sha1_file(entry->sha1, &type, &size);
 448                if (!buf)
 449                        die("unable to read %s", sha1_to_hex(entry->sha1));
 450                if (size != entry->size)
 451                        die("object %s size inconsistency (%lu vs %lu)",
 452                            sha1_to_hex(entry->sha1), size, entry->size);
 453                if (entry->delta) {
 454                        buf = delta_against(buf, size, entry);
 455                        size = entry->delta_size;
 456                        obj_type = (allow_ofs_delta && entry->delta->offset) ?
 457                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 458                }
 459                /*
 460                 * The object header is a byte of 'type' followed by zero or
 461                 * more bytes of length.
 462                 */
 463                hdrlen = encode_header(obj_type, size, header);
 464                sha1write(f, header, hdrlen);
 465
 466                if (obj_type == OBJ_OFS_DELTA) {
 467                        /*
 468                         * Deltas with relative base contain an additional
 469                         * encoding of the relative offset for the delta
 470                         * base from this object's position in the pack.
 471                         */
 472                        off_t ofs = entry->offset - entry->delta->offset;
 473                        unsigned pos = sizeof(header) - 1;
 474                        header[pos] = ofs & 127;
 475                        while (ofs >>= 7)
 476                                header[--pos] = 128 | (--ofs & 127);
 477                        sha1write(f, header + pos, sizeof(header) - pos);
 478                        hdrlen += sizeof(header) - pos;
 479                } else if (obj_type == OBJ_REF_DELTA) {
 480                        /*
 481                         * Deltas with a base reference contain
 482                         * an additional 20 bytes for the base sha1.
 483                         */
 484                        sha1write(f, entry->delta->sha1, 20);
 485                        hdrlen += 20;
 486                }
 487                datalen = sha1write_compressed(f, buf, size);
 488                free(buf);
 489        }
 490        else {
 491                struct packed_git *p = entry->in_pack;
 492                struct pack_window *w_curs = NULL;
 493                struct revindex_entry *revidx;
 494                off_t offset;
 495
 496                if (entry->delta) {
 497                        obj_type = (allow_ofs_delta && entry->delta->offset) ?
 498                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 499                        reused_delta++;
 500                }
 501                hdrlen = encode_header(obj_type, entry->size, header);
 502                sha1write(f, header, hdrlen);
 503                if (obj_type == OBJ_OFS_DELTA) {
 504                        off_t ofs = entry->offset - entry->delta->offset;
 505                        unsigned pos = sizeof(header) - 1;
 506                        header[pos] = ofs & 127;
 507                        while (ofs >>= 7)
 508                                header[--pos] = 128 | (--ofs & 127);
 509                        sha1write(f, header + pos, sizeof(header) - pos);
 510                        hdrlen += sizeof(header) - pos;
 511                } else if (obj_type == OBJ_REF_DELTA) {
 512                        sha1write(f, entry->delta->sha1, 20);
 513                        hdrlen += 20;
 514                }
 515
 516                offset = entry->in_pack_offset;
 517                revidx = find_packed_object(p, offset);
 518                datalen = revidx[1].offset - offset;
 519                if (!pack_to_stdout && p->index_version > 1 &&
 520                    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
 521                        die("bad packed object CRC for %s", sha1_to_hex(entry->sha1));
 522                offset += entry->in_pack_header_size;
 523                datalen -= entry->in_pack_header_size;
 524                if (!pack_to_stdout && p->index_version == 1 &&
 525                    check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
 526                        die("corrupt packed object for %s", sha1_to_hex(entry->sha1));
 527                copy_pack_data(f, p, &w_curs, offset, datalen);
 528                unuse_pack(&w_curs);
 529                reused++;
 530        }
 531        if (entry->delta)
 532                written_delta++;
 533        written++;
 534        if (!pack_to_stdout)
 535                entry->crc32 = crc32_end(f);
 536        return hdrlen + datalen;
 537}
 538
 539static off_t write_one(struct sha1file *f,
 540                               struct object_entry *e,
 541                               off_t offset)
 542{
 543        unsigned long size;
 544
 545        /* offset is non zero if object is written already. */
 546        if (e->offset || e->preferred_base)
 547                return offset;
 548
 549        /* if we are deltified, write out base object first. */
 550        if (e->delta)
 551                offset = write_one(f, e->delta, offset);
 552
 553        e->offset = offset;
 554        size = write_object(f, e);
 555
 556        /* make sure off_t is sufficiently large not to wrap */
 557        if (offset > offset + size)
 558                die("pack too large for current definition of off_t");
 559        return offset + size;
 560}
 561
 562static int open_object_dir_tmp(const char *path)
 563{
 564    snprintf(tmpname, sizeof(tmpname), "%s/%s", get_object_directory(), path);
 565    return mkstemp(tmpname);
 566}
 567
 568static off_t write_pack_file(void)
 569{
 570        uint32_t i;
 571        struct sha1file *f;
 572        off_t offset, last_obj_offset = 0;
 573        struct pack_header hdr;
 574        int do_progress = progress;
 575
 576        if (pack_to_stdout) {
 577                f = sha1fd(1, "<stdout>");
 578                do_progress >>= 1;
 579        } else {
 580                int fd = open_object_dir_tmp("tmp_pack_XXXXXX");
 581                if (fd < 0)
 582                        die("unable to create %s: %s\n", tmpname, strerror(errno));
 583                pack_tmp_name = xstrdup(tmpname);
 584                f = sha1fd(fd, pack_tmp_name);
 585        }
 586
 587        if (do_progress)
 588                start_progress(&progress_state, "Writing %u objects...", "", nr_result);
 589
 590        hdr.hdr_signature = htonl(PACK_SIGNATURE);
 591        hdr.hdr_version = htonl(PACK_VERSION);
 592        hdr.hdr_entries = htonl(nr_result);
 593        sha1write(f, &hdr, sizeof(hdr));
 594        offset = sizeof(hdr);
 595        if (!nr_result)
 596                goto done;
 597        for (i = 0; i < nr_objects; i++) {
 598                last_obj_offset = offset;
 599                offset = write_one(f, objects + i, offset);
 600                if (do_progress)
 601                        display_progress(&progress_state, written);
 602        }
 603        if (do_progress)
 604                stop_progress(&progress_state);
 605 done:
 606        if (written != nr_result)
 607                die("wrote %u objects while expecting %u", written, nr_result);
 608        sha1close(f, pack_file_sha1, 1);
 609
 610        return last_obj_offset;
 611}
 612
 613static int sha1_sort(const void *_a, const void *_b)
 614{
 615        const struct object_entry *a = *(struct object_entry **)_a;
 616        const struct object_entry *b = *(struct object_entry **)_b;
 617        return hashcmp(a->sha1, b->sha1);
 618}
 619
 620static uint32_t index_default_version = 1;
 621static uint32_t index_off32_limit = 0x7fffffff;
 622
 623static void write_index_file(off_t last_obj_offset, unsigned char *sha1)
 624{
 625        struct sha1file *f;
 626        struct object_entry **sorted_by_sha, **list, **last;
 627        uint32_t array[256];
 628        uint32_t i, index_version;
 629        SHA_CTX ctx;
 630
 631        int fd = open_object_dir_tmp("tmp_idx_XXXXXX");
 632        if (fd < 0)
 633                die("unable to create %s: %s\n", tmpname, strerror(errno));
 634        idx_tmp_name = xstrdup(tmpname);
 635        f = sha1fd(fd, idx_tmp_name);
 636
 637        if (nr_result) {
 638                uint32_t j = 0;
 639                sorted_by_sha =
 640                        xcalloc(nr_result, sizeof(struct object_entry *));
 641                for (i = 0; i < nr_objects; i++)
 642                        if (!objects[i].preferred_base)
 643                                sorted_by_sha[j++] = objects + i;
 644                if (j != nr_result)
 645                        die("listed %u objects while expecting %u", j, nr_result);
 646                qsort(sorted_by_sha, nr_result, sizeof(*sorted_by_sha), sha1_sort);
 647                list = sorted_by_sha;
 648                last = sorted_by_sha + nr_result;
 649        } else
 650                sorted_by_sha = list = last = NULL;
 651
 652        /* if last object's offset is >= 2^31 we should use index V2 */
 653        index_version = (last_obj_offset >> 31) ? 2 : index_default_version;
 654
 655        /* index versions 2 and above need a header */
 656        if (index_version >= 2) {
 657                struct pack_idx_header hdr;
 658                hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
 659                hdr.idx_version = htonl(index_version);
 660                sha1write(f, &hdr, sizeof(hdr));
 661        }
 662
 663        /*
 664         * Write the first-level table (the list is sorted,
 665         * but we use a 256-entry lookup to be able to avoid
 666         * having to do eight extra binary search iterations).
 667         */
 668        for (i = 0; i < 256; i++) {
 669                struct object_entry **next = list;
 670                while (next < last) {
 671                        struct object_entry *entry = *next;
 672                        if (entry->sha1[0] != i)
 673                                break;
 674                        next++;
 675                }
 676                array[i] = htonl(next - sorted_by_sha);
 677                list = next;
 678        }
 679        sha1write(f, array, 256 * 4);
 680
 681        /* Compute the SHA1 hash of sorted object names. */
 682        SHA1_Init(&ctx);
 683
 684        /* Write the actual SHA1 entries. */
 685        list = sorted_by_sha;
 686        for (i = 0; i < nr_result; i++) {
 687                struct object_entry *entry = *list++;
 688                if (index_version < 2) {
 689                        uint32_t offset = htonl(entry->offset);
 690                        sha1write(f, &offset, 4);
 691                }
 692                sha1write(f, entry->sha1, 20);
 693                SHA1_Update(&ctx, entry->sha1, 20);
 694        }
 695
 696        if (index_version >= 2) {
 697                unsigned int nr_large_offset = 0;
 698
 699                /* write the crc32 table */
 700                list = sorted_by_sha;
 701                for (i = 0; i < nr_objects; i++) {
 702                        struct object_entry *entry = *list++;
 703                        uint32_t crc32_val = htonl(entry->crc32);
 704                        sha1write(f, &crc32_val, 4);
 705                }
 706
 707                /* write the 32-bit offset table */
 708                list = sorted_by_sha;
 709                for (i = 0; i < nr_objects; i++) {
 710                        struct object_entry *entry = *list++;
 711                        uint32_t offset = (entry->offset <= index_off32_limit) ?
 712                                entry->offset : (0x80000000 | nr_large_offset++);
 713                        offset = htonl(offset);
 714                        sha1write(f, &offset, 4);
 715                }
 716
 717                /* write the large offset table */
 718                list = sorted_by_sha;
 719                while (nr_large_offset) {
 720                        struct object_entry *entry = *list++;
 721                        uint64_t offset = entry->offset;
 722                        if (offset > index_off32_limit) {
 723                                uint32_t split[2];
 724                                split[0]        = htonl(offset >> 32);
 725                                split[1] = htonl(offset & 0xffffffff);
 726                                sha1write(f, split, 8);
 727                                nr_large_offset--;
 728                        }
 729                }
 730        }
 731
 732        sha1write(f, pack_file_sha1, 20);
 733        sha1close(f, NULL, 1);
 734        free(sorted_by_sha);
 735        SHA1_Final(sha1, &ctx);
 736}
 737
 738static int locate_object_entry_hash(const unsigned char *sha1)
 739{
 740        int i;
 741        unsigned int ui;
 742        memcpy(&ui, sha1, sizeof(unsigned int));
 743        i = ui % object_ix_hashsz;
 744        while (0 < object_ix[i]) {
 745                if (!hashcmp(sha1, objects[object_ix[i] - 1].sha1))
 746                        return i;
 747                if (++i == object_ix_hashsz)
 748                        i = 0;
 749        }
 750        return -1 - i;
 751}
 752
 753static struct object_entry *locate_object_entry(const unsigned char *sha1)
 754{
 755        int i;
 756
 757        if (!object_ix_hashsz)
 758                return NULL;
 759
 760        i = locate_object_entry_hash(sha1);
 761        if (0 <= i)
 762                return &objects[object_ix[i]-1];
 763        return NULL;
 764}
 765
 766static void rehash_objects(void)
 767{
 768        uint32_t i;
 769        struct object_entry *oe;
 770
 771        object_ix_hashsz = nr_objects * 3;
 772        if (object_ix_hashsz < 1024)
 773                object_ix_hashsz = 1024;
 774        object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 775        memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 776        for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 777                int ix = locate_object_entry_hash(oe->sha1);
 778                if (0 <= ix)
 779                        continue;
 780                ix = -1 - ix;
 781                object_ix[ix] = i + 1;
 782        }
 783}
 784
 785static unsigned name_hash(const char *name)
 786{
 787        unsigned char c;
 788        unsigned hash = 0;
 789
 790        /*
 791         * This effectively just creates a sortable number from the
 792         * last sixteen non-whitespace characters. Last characters
 793         * count "most", so things that end in ".c" sort together.
 794         */
 795        while ((c = *name++) != 0) {
 796                if (isspace(c))
 797                        continue;
 798                hash = (hash >> 2) + (c << 24);
 799        }
 800        return hash;
 801}
 802
 803static int add_object_entry(const unsigned char *sha1, enum object_type type,
 804                            unsigned hash, int exclude)
 805{
 806        struct object_entry *entry;
 807        struct packed_git *p, *found_pack = NULL;
 808        off_t found_offset = 0;
 809        int ix;
 810
 811        ix = nr_objects ? locate_object_entry_hash(sha1) : -1;
 812        if (ix >= 0) {
 813                if (exclude) {
 814                        entry = objects + object_ix[ix] - 1;
 815                        if (!entry->preferred_base)
 816                                nr_result--;
 817                        entry->preferred_base = 1;
 818                }
 819                return 0;
 820        }
 821
 822        for (p = packed_git; p; p = p->next) {
 823                off_t offset = find_pack_entry_one(sha1, p);
 824                if (offset) {
 825                        if (!found_pack) {
 826                                found_offset = offset;
 827                                found_pack = p;
 828                        }
 829                        if (exclude)
 830                                break;
 831                        if (incremental)
 832                                return 0;
 833                        if (local && !p->pack_local)
 834                                return 0;
 835                }
 836        }
 837
 838        if (nr_objects >= nr_alloc) {
 839                nr_alloc = (nr_alloc  + 1024) * 3 / 2;
 840                objects = xrealloc(objects, nr_alloc * sizeof(*entry));
 841        }
 842
 843        entry = objects + nr_objects++;
 844        memset(entry, 0, sizeof(*entry));
 845        hashcpy(entry->sha1, sha1);
 846        entry->hash = hash;
 847        if (type)
 848                entry->type = type;
 849        if (exclude)
 850                entry->preferred_base = 1;
 851        else
 852                nr_result++;
 853        if (found_pack) {
 854                entry->in_pack = found_pack;
 855                entry->in_pack_offset = found_offset;
 856        }
 857
 858        if (object_ix_hashsz * 3 <= nr_objects * 4)
 859                rehash_objects();
 860        else
 861                object_ix[-1 - ix] = nr_objects;
 862
 863        if (progress)
 864                display_progress(&progress_state, nr_objects);
 865
 866        return 1;
 867}
 868
 869struct pbase_tree_cache {
 870        unsigned char sha1[20];
 871        int ref;
 872        int temporary;
 873        void *tree_data;
 874        unsigned long tree_size;
 875};
 876
 877static struct pbase_tree_cache *(pbase_tree_cache[256]);
 878static int pbase_tree_cache_ix(const unsigned char *sha1)
 879{
 880        return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 881}
 882static int pbase_tree_cache_ix_incr(int ix)
 883{
 884        return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 885}
 886
 887static struct pbase_tree {
 888        struct pbase_tree *next;
 889        /* This is a phony "cache" entry; we are not
 890         * going to evict it nor find it through _get()
 891         * mechanism -- this is for the toplevel node that
 892         * would almost always change with any commit.
 893         */
 894        struct pbase_tree_cache pcache;
 895} *pbase_tree;
 896
 897static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 898{
 899        struct pbase_tree_cache *ent, *nent;
 900        void *data;
 901        unsigned long size;
 902        enum object_type type;
 903        int neigh;
 904        int my_ix = pbase_tree_cache_ix(sha1);
 905        int available_ix = -1;
 906
 907        /* pbase-tree-cache acts as a limited hashtable.
 908         * your object will be found at your index or within a few
 909         * slots after that slot if it is cached.
 910         */
 911        for (neigh = 0; neigh < 8; neigh++) {
 912                ent = pbase_tree_cache[my_ix];
 913                if (ent && !hashcmp(ent->sha1, sha1)) {
 914                        ent->ref++;
 915                        return ent;
 916                }
 917                else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 918                         ((0 <= available_ix) &&
 919                          (!ent && pbase_tree_cache[available_ix])))
 920                        available_ix = my_ix;
 921                if (!ent)
 922                        break;
 923                my_ix = pbase_tree_cache_ix_incr(my_ix);
 924        }
 925
 926        /* Did not find one.  Either we got a bogus request or
 927         * we need to read and perhaps cache.
 928         */
 929        data = read_sha1_file(sha1, &type, &size);
 930        if (!data)
 931                return NULL;
 932        if (type != OBJ_TREE) {
 933                free(data);
 934                return NULL;
 935        }
 936
 937        /* We need to either cache or return a throwaway copy */
 938
 939        if (available_ix < 0)
 940                ent = NULL;
 941        else {
 942                ent = pbase_tree_cache[available_ix];
 943                my_ix = available_ix;
 944        }
 945
 946        if (!ent) {
 947                nent = xmalloc(sizeof(*nent));
 948                nent->temporary = (available_ix < 0);
 949        }
 950        else {
 951                /* evict and reuse */
 952                free(ent->tree_data);
 953                nent = ent;
 954        }
 955        hashcpy(nent->sha1, sha1);
 956        nent->tree_data = data;
 957        nent->tree_size = size;
 958        nent->ref = 1;
 959        if (!nent->temporary)
 960                pbase_tree_cache[my_ix] = nent;
 961        return nent;
 962}
 963
 964static void pbase_tree_put(struct pbase_tree_cache *cache)
 965{
 966        if (!cache->temporary) {
 967                cache->ref--;
 968                return;
 969        }
 970        free(cache->tree_data);
 971        free(cache);
 972}
 973
 974static int name_cmp_len(const char *name)
 975{
 976        int i;
 977        for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 978                ;
 979        return i;
 980}
 981
 982static void add_pbase_object(struct tree_desc *tree,
 983                             const char *name,
 984                             int cmplen,
 985                             const char *fullname)
 986{
 987        struct name_entry entry;
 988        int cmp;
 989
 990        while (tree_entry(tree,&entry)) {
 991                cmp = tree_entry_len(entry.path, entry.sha1) != cmplen ? 1 :
 992                      memcmp(name, entry.path, cmplen);
 993                if (cmp > 0)
 994                        continue;
 995                if (cmp < 0)
 996                        return;
 997                if (name[cmplen] != '/') {
 998                        unsigned hash = name_hash(fullname);
 999                        add_object_entry(entry.sha1,
1000                                         S_ISDIR(entry.mode) ? OBJ_TREE : OBJ_BLOB,
1001                                         hash, 1);
1002                        return;
1003                }
1004                if (S_ISDIR(entry.mode)) {
1005                        struct tree_desc sub;
1006                        struct pbase_tree_cache *tree;
1007                        const char *down = name+cmplen+1;
1008                        int downlen = name_cmp_len(down);
1009
1010                        tree = pbase_tree_get(entry.sha1);
1011                        if (!tree)
1012                                return;
1013                        init_tree_desc(&sub, tree->tree_data, tree->tree_size);
1014
1015                        add_pbase_object(&sub, down, downlen, fullname);
1016                        pbase_tree_put(tree);
1017                }
1018        }
1019}
1020
1021static unsigned *done_pbase_paths;
1022static int done_pbase_paths_num;
1023static int done_pbase_paths_alloc;
1024static int done_pbase_path_pos(unsigned hash)
1025{
1026        int lo = 0;
1027        int hi = done_pbase_paths_num;
1028        while (lo < hi) {
1029                int mi = (hi + lo) / 2;
1030                if (done_pbase_paths[mi] == hash)
1031                        return mi;
1032                if (done_pbase_paths[mi] < hash)
1033                        hi = mi;
1034                else
1035                        lo = mi + 1;
1036        }
1037        return -lo-1;
1038}
1039
1040static int check_pbase_path(unsigned hash)
1041{
1042        int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
1043        if (0 <= pos)
1044                return 1;
1045        pos = -pos - 1;
1046        if (done_pbase_paths_alloc <= done_pbase_paths_num) {
1047                done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
1048                done_pbase_paths = xrealloc(done_pbase_paths,
1049                                            done_pbase_paths_alloc *
1050                                            sizeof(unsigned));
1051        }
1052        done_pbase_paths_num++;
1053        if (pos < done_pbase_paths_num)
1054                memmove(done_pbase_paths + pos + 1,
1055                        done_pbase_paths + pos,
1056                        (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
1057        done_pbase_paths[pos] = hash;
1058        return 0;
1059}
1060
1061static void add_preferred_base_object(const char *name, unsigned hash)
1062{
1063        struct pbase_tree *it;
1064        int cmplen;
1065
1066        if (!num_preferred_base || check_pbase_path(hash))
1067                return;
1068
1069        cmplen = name_cmp_len(name);
1070        for (it = pbase_tree; it; it = it->next) {
1071                if (cmplen == 0) {
1072                        add_object_entry(it->pcache.sha1, OBJ_TREE, 0, 1);
1073                }
1074                else {
1075                        struct tree_desc tree;
1076                        init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
1077                        add_pbase_object(&tree, name, cmplen, name);
1078                }
1079        }
1080}
1081
1082static void add_preferred_base(unsigned char *sha1)
1083{
1084        struct pbase_tree *it;
1085        void *data;
1086        unsigned long size;
1087        unsigned char tree_sha1[20];
1088
1089        if (window <= num_preferred_base++)
1090                return;
1091
1092        data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
1093        if (!data)
1094                return;
1095
1096        for (it = pbase_tree; it; it = it->next) {
1097                if (!hashcmp(it->pcache.sha1, tree_sha1)) {
1098                        free(data);
1099                        return;
1100                }
1101        }
1102
1103        it = xcalloc(1, sizeof(*it));
1104        it->next = pbase_tree;
1105        pbase_tree = it;
1106
1107        hashcpy(it->pcache.sha1, tree_sha1);
1108        it->pcache.tree_data = data;
1109        it->pcache.tree_size = size;
1110}
1111
1112static void check_object(struct object_entry *entry)
1113{
1114        if (entry->in_pack) {
1115                struct packed_git *p = entry->in_pack;
1116                struct pack_window *w_curs = NULL;
1117                const unsigned char *base_ref = NULL;
1118                struct object_entry *base_entry;
1119                unsigned long used, used_0;
1120                unsigned int avail;
1121                off_t ofs;
1122                unsigned char *buf, c;
1123
1124                buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
1125
1126                /*
1127                 * We want in_pack_type even if we do not reuse delta.
1128                 * There is no point not reusing non-delta representations.
1129                 */
1130                used = unpack_object_header_gently(buf, avail,
1131                                                   &entry->in_pack_type,
1132                                                   &entry->size);
1133
1134                /*
1135                 * Determine if this is a delta and if so whether we can
1136                 * reuse it or not.  Otherwise let's find out as cheaply as
1137                 * possible what the actual type and size for this object is.
1138                 */
1139                switch (entry->in_pack_type) {
1140                default:
1141                        /* Not a delta hence we've already got all we need. */
1142                        entry->type = entry->in_pack_type;
1143                        entry->in_pack_header_size = used;
1144                        unuse_pack(&w_curs);
1145                        return;
1146                case OBJ_REF_DELTA:
1147                        if (!no_reuse_delta && !entry->preferred_base)
1148                                base_ref = use_pack(p, &w_curs,
1149                                                entry->in_pack_offset + used, NULL);
1150                        entry->in_pack_header_size = used + 20;
1151                        break;
1152                case OBJ_OFS_DELTA:
1153                        buf = use_pack(p, &w_curs,
1154                                       entry->in_pack_offset + used, NULL);
1155                        used_0 = 0;
1156                        c = buf[used_0++];
1157                        ofs = c & 127;
1158                        while (c & 128) {
1159                                ofs += 1;
1160                                if (!ofs || MSB(ofs, 7))
1161                                        die("delta base offset overflow in pack for %s",
1162                                            sha1_to_hex(entry->sha1));
1163                                c = buf[used_0++];
1164                                ofs = (ofs << 7) + (c & 127);
1165                        }
1166                        if (ofs >= entry->in_pack_offset)
1167                                die("delta base offset out of bound for %s",
1168                                    sha1_to_hex(entry->sha1));
1169                        ofs = entry->in_pack_offset - ofs;
1170                        if (!no_reuse_delta && !entry->preferred_base)
1171                                base_ref = find_packed_object_name(p, ofs);
1172                        entry->in_pack_header_size = used + used_0;
1173                        break;
1174                }
1175
1176                if (base_ref && (base_entry = locate_object_entry(base_ref))) {
1177                        /*
1178                         * If base_ref was set above that means we wish to
1179                         * reuse delta data, and we even found that base
1180                         * in the list of objects we want to pack. Goodie!
1181                         *
1182                         * Depth value does not matter - find_deltas() will
1183                         * never consider reused delta as the base object to
1184                         * deltify other objects against, in order to avoid
1185                         * circular deltas.
1186                         */
1187                        entry->type = entry->in_pack_type;
1188                        entry->delta = base_entry;
1189                        entry->delta_sibling = base_entry->delta_child;
1190                        base_entry->delta_child = entry;
1191                        unuse_pack(&w_curs);
1192                        return;
1193                }
1194
1195                if (entry->type) {
1196                        /*
1197                         * This must be a delta and we already know what the
1198                         * final object type is.  Let's extract the actual
1199                         * object size from the delta header.
1200                         */
1201                        entry->size = get_size_from_delta(p, &w_curs,
1202                                        entry->in_pack_offset + entry->in_pack_header_size);
1203                        unuse_pack(&w_curs);
1204                        return;
1205                }
1206
1207                /*
1208                 * No choice but to fall back to the recursive delta walk
1209                 * with sha1_object_info() to find about the object type
1210                 * at this point...
1211                 */
1212                unuse_pack(&w_curs);
1213        }
1214
1215        entry->type = sha1_object_info(entry->sha1, &entry->size);
1216        if (entry->type < 0)
1217                die("unable to get type of object %s",
1218                    sha1_to_hex(entry->sha1));
1219}
1220
1221static int pack_offset_sort(const void *_a, const void *_b)
1222{
1223        const struct object_entry *a = *(struct object_entry **)_a;
1224        const struct object_entry *b = *(struct object_entry **)_b;
1225
1226        /* avoid filesystem trashing with loose objects */
1227        if (!a->in_pack && !b->in_pack)
1228                return hashcmp(a->sha1, b->sha1);
1229
1230        if (a->in_pack < b->in_pack)
1231                return -1;
1232        if (a->in_pack > b->in_pack)
1233                return 1;
1234        return a->in_pack_offset < b->in_pack_offset ? -1 :
1235                        (a->in_pack_offset > b->in_pack_offset);
1236}
1237
1238static void get_object_details(void)
1239{
1240        uint32_t i;
1241        struct object_entry **sorted_by_offset;
1242
1243        sorted_by_offset = xcalloc(nr_objects, sizeof(struct object_entry *));
1244        for (i = 0; i < nr_objects; i++)
1245                sorted_by_offset[i] = objects + i;
1246        qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
1247
1248        prepare_pack_ix();
1249        for (i = 0; i < nr_objects; i++)
1250                check_object(sorted_by_offset[i]);
1251        free(sorted_by_offset);
1252}
1253
1254static int type_size_sort(const void *_a, const void *_b)
1255{
1256        const struct object_entry *a = *(struct object_entry **)_a;
1257        const struct object_entry *b = *(struct object_entry **)_b;
1258
1259        if (a->type < b->type)
1260                return -1;
1261        if (a->type > b->type)
1262                return 1;
1263        if (a->hash < b->hash)
1264                return -1;
1265        if (a->hash > b->hash)
1266                return 1;
1267        if (a->preferred_base < b->preferred_base)
1268                return -1;
1269        if (a->preferred_base > b->preferred_base)
1270                return 1;
1271        if (a->size < b->size)
1272                return -1;
1273        if (a->size > b->size)
1274                return 1;
1275        return a > b ? -1 : (a < b);  /* newest last */
1276}
1277
1278struct unpacked {
1279        struct object_entry *entry;
1280        void *data;
1281        struct delta_index *index;
1282};
1283
1284/*
1285 * We search for deltas _backwards_ in a list sorted by type and
1286 * by size, so that we see progressively smaller and smaller files.
1287 * That's because we prefer deltas to be from the bigger file
1288 * to the smaller - deletes are potentially cheaper, but perhaps
1289 * more importantly, the bigger file is likely the more recent
1290 * one.
1291 */
1292static int try_delta(struct unpacked *trg, struct unpacked *src,
1293                     unsigned max_depth)
1294{
1295        struct object_entry *trg_entry = trg->entry;
1296        struct object_entry *src_entry = src->entry;
1297        unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
1298        enum object_type type;
1299        void *delta_buf;
1300
1301        /* Don't bother doing diffs between different types */
1302        if (trg_entry->type != src_entry->type)
1303                return -1;
1304
1305        /* We do not compute delta to *create* objects we are not
1306         * going to pack.
1307         */
1308        if (trg_entry->preferred_base)
1309                return -1;
1310
1311        /*
1312         * We do not bother to try a delta that we discarded
1313         * on an earlier try, but only when reusing delta data.
1314         */
1315        if (!no_reuse_delta && trg_entry->in_pack &&
1316            trg_entry->in_pack == src_entry->in_pack &&
1317            trg_entry->in_pack_type != OBJ_REF_DELTA &&
1318            trg_entry->in_pack_type != OBJ_OFS_DELTA)
1319                return 0;
1320
1321        /* Let's not bust the allowed depth. */
1322        if (src_entry->depth >= max_depth)
1323                return 0;
1324
1325        /* Now some size filtering heuristics. */
1326        trg_size = trg_entry->size;
1327        max_size = trg_size/2 - 20;
1328        max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1329        if (max_size == 0)
1330                return 0;
1331        if (trg_entry->delta && trg_entry->delta_size <= max_size)
1332                max_size = trg_entry->delta_size-1;
1333        src_size = src_entry->size;
1334        sizediff = src_size < trg_size ? trg_size - src_size : 0;
1335        if (sizediff >= max_size)
1336                return 0;
1337
1338        /* Load data if not already done */
1339        if (!trg->data) {
1340                trg->data = read_sha1_file(trg_entry->sha1, &type, &sz);
1341                if (sz != trg_size)
1342                        die("object %s inconsistent object length (%lu vs %lu)",
1343                            sha1_to_hex(trg_entry->sha1), sz, trg_size);
1344        }
1345        if (!src->data) {
1346                src->data = read_sha1_file(src_entry->sha1, &type, &sz);
1347                if (sz != src_size)
1348                        die("object %s inconsistent object length (%lu vs %lu)",
1349                            sha1_to_hex(src_entry->sha1), sz, src_size);
1350        }
1351        if (!src->index) {
1352                src->index = create_delta_index(src->data, src_size);
1353                if (!src->index)
1354                        die("out of memory");
1355        }
1356
1357        delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1358        if (!delta_buf)
1359                return 0;
1360
1361        trg_entry->delta = src_entry;
1362        trg_entry->delta_size = delta_size;
1363        trg_entry->depth = src_entry->depth + 1;
1364        free(delta_buf);
1365        return 1;
1366}
1367
1368static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
1369{
1370        struct object_entry *child = me->delta_child;
1371        unsigned int m = n;
1372        while (child) {
1373                unsigned int c = check_delta_limit(child, n + 1);
1374                if (m < c)
1375                        m = c;
1376                child = child->delta_sibling;
1377        }
1378        return m;
1379}
1380
1381static void find_deltas(struct object_entry **list, int window, int depth)
1382{
1383        uint32_t i = nr_objects, idx = 0, processed = 0;
1384        unsigned int array_size = window * sizeof(struct unpacked);
1385        struct unpacked *array;
1386        int max_depth;
1387
1388        if (!nr_objects)
1389                return;
1390        array = xmalloc(array_size);
1391        memset(array, 0, array_size);
1392        if (progress)
1393                start_progress(&progress_state, "Deltifying %u objects...", "", nr_result);
1394
1395        do {
1396                struct object_entry *entry = list[--i];
1397                struct unpacked *n = array + idx;
1398                int j;
1399
1400                if (!entry->preferred_base)
1401                        processed++;
1402
1403                if (progress)
1404                        display_progress(&progress_state, processed);
1405
1406                if (entry->delta)
1407                        /* This happens if we decided to reuse existing
1408                         * delta from a pack.  "!no_reuse_delta &&" is implied.
1409                         */
1410                        continue;
1411
1412                if (entry->size < 50)
1413                        continue;
1414                free_delta_index(n->index);
1415                n->index = NULL;
1416                free(n->data);
1417                n->data = NULL;
1418                n->entry = entry;
1419
1420                /*
1421                 * If the current object is at pack edge, take the depth the
1422                 * objects that depend on the current object into account
1423                 * otherwise they would become too deep.
1424                 */
1425                max_depth = depth;
1426                if (entry->delta_child) {
1427                        max_depth -= check_delta_limit(entry, 0);
1428                        if (max_depth <= 0)
1429                                goto next;
1430                }
1431
1432                j = window;
1433                while (--j > 0) {
1434                        uint32_t other_idx = idx + j;
1435                        struct unpacked *m;
1436                        if (other_idx >= window)
1437                                other_idx -= window;
1438                        m = array + other_idx;
1439                        if (!m->entry)
1440                                break;
1441                        if (try_delta(n, m, max_depth) < 0)
1442                                break;
1443                }
1444
1445                /* if we made n a delta, and if n is already at max
1446                 * depth, leaving it in the window is pointless.  we
1447                 * should evict it first.
1448                 */
1449                if (entry->delta && depth <= entry->depth)
1450                        continue;
1451
1452                next:
1453                idx++;
1454                if (idx >= window)
1455                        idx = 0;
1456        } while (i > 0);
1457
1458        if (progress)
1459                stop_progress(&progress_state);
1460
1461        for (i = 0; i < window; ++i) {
1462                free_delta_index(array[i].index);
1463                free(array[i].data);
1464        }
1465        free(array);
1466}
1467
1468static void prepare_pack(int window, int depth)
1469{
1470        struct object_entry **delta_list;
1471        uint32_t i;
1472
1473        get_object_details();
1474
1475        if (!window || !depth)
1476                return;
1477
1478        delta_list = xmalloc(nr_objects * sizeof(*delta_list));
1479        for (i = 0; i < nr_objects; i++)
1480                delta_list[i] = objects + i;
1481        qsort(delta_list, nr_objects, sizeof(*delta_list), type_size_sort);
1482        find_deltas(delta_list, window+1, depth);
1483        free(delta_list);
1484}
1485
1486static int git_pack_config(const char *k, const char *v)
1487{
1488        if(!strcmp(k, "pack.window")) {
1489                window = git_config_int(k, v);
1490                return 0;
1491        }
1492        return git_default_config(k, v);
1493}
1494
1495static void read_object_list_from_stdin(void)
1496{
1497        char line[40 + 1 + PATH_MAX + 2];
1498        unsigned char sha1[20];
1499        unsigned hash;
1500
1501        for (;;) {
1502                if (!fgets(line, sizeof(line), stdin)) {
1503                        if (feof(stdin))
1504                                break;
1505                        if (!ferror(stdin))
1506                                die("fgets returned NULL, not EOF, not error!");
1507                        if (errno != EINTR)
1508                                die("fgets: %s", strerror(errno));
1509                        clearerr(stdin);
1510                        continue;
1511                }
1512                if (line[0] == '-') {
1513                        if (get_sha1_hex(line+1, sha1))
1514                                die("expected edge sha1, got garbage:\n %s",
1515                                    line);
1516                        add_preferred_base(sha1);
1517                        continue;
1518                }
1519                if (get_sha1_hex(line, sha1))
1520                        die("expected sha1, got garbage:\n %s", line);
1521
1522                hash = name_hash(line+41);
1523                add_preferred_base_object(line+41, hash);
1524                add_object_entry(sha1, 0, hash, 0);
1525        }
1526}
1527
1528static void show_commit(struct commit *commit)
1529{
1530        add_object_entry(commit->object.sha1, OBJ_COMMIT, 0, 0);
1531}
1532
1533static void show_object(struct object_array_entry *p)
1534{
1535        unsigned hash = name_hash(p->name);
1536        add_preferred_base_object(p->name, hash);
1537        add_object_entry(p->item->sha1, p->item->type, hash, 0);
1538}
1539
1540static void show_edge(struct commit *commit)
1541{
1542        add_preferred_base(commit->object.sha1);
1543}
1544
1545static void get_object_list(int ac, const char **av)
1546{
1547        struct rev_info revs;
1548        char line[1000];
1549        int flags = 0;
1550
1551        init_revisions(&revs, NULL);
1552        save_commit_buffer = 0;
1553        track_object_refs = 0;
1554        setup_revisions(ac, av, &revs, NULL);
1555
1556        while (fgets(line, sizeof(line), stdin) != NULL) {
1557                int len = strlen(line);
1558                if (line[len - 1] == '\n')
1559                        line[--len] = 0;
1560                if (!len)
1561                        break;
1562                if (*line == '-') {
1563                        if (!strcmp(line, "--not")) {
1564                                flags ^= UNINTERESTING;
1565                                continue;
1566                        }
1567                        die("not a rev '%s'", line);
1568                }
1569                if (handle_revision_arg(line, &revs, flags, 1))
1570                        die("bad revision '%s'", line);
1571        }
1572
1573        prepare_revision_walk(&revs);
1574        mark_edges_uninteresting(revs.commits, &revs, show_edge);
1575        traverse_commit_list(&revs, show_commit, show_object);
1576}
1577
1578static int adjust_perm(const char *path, mode_t mode)
1579{
1580        if (chmod(path, mode))
1581                return -1;
1582        return adjust_shared_perm(path);
1583}
1584
1585int cmd_pack_objects(int argc, const char **argv, const char *prefix)
1586{
1587        int depth = 10;
1588        int use_internal_rev_list = 0;
1589        int thin = 0;
1590        uint32_t i;
1591        off_t last_obj_offset;
1592        const char *base_name = NULL;
1593        const char **rp_av;
1594        int rp_ac_alloc = 64;
1595        int rp_ac;
1596
1597        rp_av = xcalloc(rp_ac_alloc, sizeof(*rp_av));
1598
1599        rp_av[0] = "pack-objects";
1600        rp_av[1] = "--objects"; /* --thin will make it --objects-edge */
1601        rp_ac = 2;
1602
1603        git_config(git_pack_config);
1604
1605        progress = isatty(2);
1606        for (i = 1; i < argc; i++) {
1607                const char *arg = argv[i];
1608
1609                if (*arg != '-')
1610                        break;
1611
1612                if (!strcmp("--non-empty", arg)) {
1613                        non_empty = 1;
1614                        continue;
1615                }
1616                if (!strcmp("--local", arg)) {
1617                        local = 1;
1618                        continue;
1619                }
1620                if (!strcmp("--incremental", arg)) {
1621                        incremental = 1;
1622                        continue;
1623                }
1624                if (!prefixcmp(arg, "--window=")) {
1625                        char *end;
1626                        window = strtoul(arg+9, &end, 0);
1627                        if (!arg[9] || *end)
1628                                usage(pack_usage);
1629                        continue;
1630                }
1631                if (!prefixcmp(arg, "--depth=")) {
1632                        char *end;
1633                        depth = strtoul(arg+8, &end, 0);
1634                        if (!arg[8] || *end)
1635                                usage(pack_usage);
1636                        continue;
1637                }
1638                if (!strcmp("--progress", arg)) {
1639                        progress = 1;
1640                        continue;
1641                }
1642                if (!strcmp("--all-progress", arg)) {
1643                        progress = 2;
1644                        continue;
1645                }
1646                if (!strcmp("-q", arg)) {
1647                        progress = 0;
1648                        continue;
1649                }
1650                if (!strcmp("--no-reuse-delta", arg)) {
1651                        no_reuse_delta = 1;
1652                        continue;
1653                }
1654                if (!strcmp("--delta-base-offset", arg)) {
1655                        allow_ofs_delta = 1;
1656                        continue;
1657                }
1658                if (!strcmp("--stdout", arg)) {
1659                        pack_to_stdout = 1;
1660                        continue;
1661                }
1662                if (!strcmp("--revs", arg)) {
1663                        use_internal_rev_list = 1;
1664                        continue;
1665                }
1666                if (!strcmp("--unpacked", arg) ||
1667                    !prefixcmp(arg, "--unpacked=") ||
1668                    !strcmp("--reflog", arg) ||
1669                    !strcmp("--all", arg)) {
1670                        use_internal_rev_list = 1;
1671                        if (rp_ac >= rp_ac_alloc - 1) {
1672                                rp_ac_alloc = alloc_nr(rp_ac_alloc);
1673                                rp_av = xrealloc(rp_av,
1674                                                 rp_ac_alloc * sizeof(*rp_av));
1675                        }
1676                        rp_av[rp_ac++] = arg;
1677                        continue;
1678                }
1679                if (!strcmp("--thin", arg)) {
1680                        use_internal_rev_list = 1;
1681                        thin = 1;
1682                        rp_av[1] = "--objects-edge";
1683                        continue;
1684                }
1685                if (!prefixcmp(arg, "--index-version=")) {
1686                        char *c;
1687                        index_default_version = strtoul(arg + 16, &c, 10);
1688                        if (index_default_version > 2)
1689                                die("bad %s", arg);
1690                        if (*c == ',')
1691                                index_off32_limit = strtoul(c+1, &c, 0);
1692                        if (*c || index_off32_limit & 0x80000000)
1693                                die("bad %s", arg);
1694                        continue;
1695                }
1696                usage(pack_usage);
1697        }
1698
1699        /* Traditionally "pack-objects [options] base extra" failed;
1700         * we would however want to take refs parameter that would
1701         * have been given to upstream rev-list ourselves, which means
1702         * we somehow want to say what the base name is.  So the
1703         * syntax would be:
1704         *
1705         * pack-objects [options] base <refs...>
1706         *
1707         * in other words, we would treat the first non-option as the
1708         * base_name and send everything else to the internal revision
1709         * walker.
1710         */
1711
1712        if (!pack_to_stdout)
1713                base_name = argv[i++];
1714
1715        if (pack_to_stdout != !base_name)
1716                usage(pack_usage);
1717
1718        if (!pack_to_stdout && thin)
1719                die("--thin cannot be used to build an indexable pack.");
1720
1721        prepare_packed_git();
1722
1723        if (progress)
1724                start_progress(&progress_state, "Generating pack...",
1725                               "Counting objects: ", 0);
1726        if (!use_internal_rev_list)
1727                read_object_list_from_stdin();
1728        else {
1729                rp_av[rp_ac] = NULL;
1730                get_object_list(rp_ac, rp_av);
1731        }
1732        if (progress) {
1733                stop_progress(&progress_state);
1734                fprintf(stderr, "Done counting %u objects.\n", nr_objects);
1735        }
1736
1737        if (non_empty && !nr_result)
1738                return 0;
1739        if (progress && (nr_objects != nr_result))
1740                fprintf(stderr, "Result has %u objects.\n", nr_result);
1741        if (nr_result)
1742                prepare_pack(window, depth);
1743        last_obj_offset = write_pack_file();
1744        if (!pack_to_stdout) {
1745                unsigned char object_list_sha1[20];
1746                mode_t mode = umask(0);
1747
1748                umask(mode);
1749                mode = 0444 & ~mode;
1750
1751                write_index_file(last_obj_offset, object_list_sha1);
1752                snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
1753                         base_name, sha1_to_hex(object_list_sha1));
1754                if (adjust_perm(pack_tmp_name, mode))
1755                        die("unable to make temporary pack file readable: %s",
1756                            strerror(errno));
1757                if (rename(pack_tmp_name, tmpname))
1758                        die("unable to rename temporary pack file: %s",
1759                            strerror(errno));
1760                snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
1761                         base_name, sha1_to_hex(object_list_sha1));
1762                if (adjust_perm(idx_tmp_name, mode))
1763                        die("unable to make temporary index file readable: %s",
1764                            strerror(errno));
1765                if (rename(idx_tmp_name, tmpname))
1766                        die("unable to rename temporary index file: %s",
1767                            strerror(errno));
1768                puts(sha1_to_hex(object_list_sha1));
1769        }
1770        if (progress)
1771                fprintf(stderr, "Total %u (delta %u), reused %u (delta %u)\n",
1772                        written, written_delta, reused, reused_delta);
1773        return 0;
1774}