builtin-pack-objects.con commit rearrange delta search progress reporting (e334977)
   1#include "builtin.h"
   2#include "cache.h"
   3#include "attr.h"
   4#include "object.h"
   5#include "blob.h"
   6#include "commit.h"
   7#include "tag.h"
   8#include "tree.h"
   9#include "delta.h"
  10#include "pack.h"
  11#include "csum-file.h"
  12#include "tree-walk.h"
  13#include "diff.h"
  14#include "revision.h"
  15#include "list-objects.h"
  16#include "progress.h"
  17
  18static const char pack_usage[] = "\
  19git-pack-objects [{ -q | --progress | --all-progress }] \n\
  20        [--max-pack-size=N] [--local] [--incremental] \n\
  21        [--window=N] [--window-memory=N] [--depth=N] \n\
  22        [--no-reuse-delta] [--no-reuse-object] [--delta-base-offset] \n\
  23        [--non-empty] [--revs [--unpacked | --all]*] [--reflog] \n\
  24        [--stdout | base-name] [<ref-list | <object-list]";
  25
  26struct object_entry {
  27        struct pack_idx_entry idx;
  28        unsigned long size;     /* uncompressed size */
  29        struct packed_git *in_pack;     /* already in pack */
  30        off_t in_pack_offset;
  31        struct object_entry *delta;     /* delta base object */
  32        struct object_entry *delta_child; /* deltified objects who bases me */
  33        struct object_entry *delta_sibling; /* other deltified objects who
  34                                             * uses the same base as me
  35                                             */
  36        void *delta_data;       /* cached delta (uncompressed) */
  37        unsigned long delta_size;       /* delta data size (uncompressed) */
  38        unsigned int hash;      /* name hint hash */
  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 object to delta
  44                                       * objects against.
  45                                       */
  46        unsigned char no_try_delta;
  47};
  48
  49/*
  50 * Objects we are going to pack are collected in objects array (dynamically
  51 * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  52 * in the order we see -- typically rev-list --objects order that gives us
  53 * nice "minimum seek" order.
  54 */
  55static struct object_entry *objects;
  56static struct object_entry **written_list;
  57static uint32_t nr_objects, nr_alloc, nr_result, nr_written;
  58
  59static int non_empty;
  60static int no_reuse_delta, no_reuse_object;
  61static int local;
  62static int incremental;
  63static int allow_ofs_delta;
  64static const char *pack_tmp_name, *idx_tmp_name;
  65static char tmpname[PATH_MAX];
  66static const char *base_name;
  67static int progress = 1;
  68static int window = 10;
  69static uint32_t pack_size_limit;
  70static int depth = 50;
  71static int pack_to_stdout;
  72static int num_preferred_base;
  73static struct progress progress_state;
  74static int pack_compression_level = Z_DEFAULT_COMPRESSION;
  75static int pack_compression_seen;
  76
  77static unsigned long delta_cache_size = 0;
  78static unsigned long max_delta_cache_size = 0;
  79static unsigned long cache_max_small_delta_size = 1000;
  80
  81static unsigned long window_memory_limit = 0;
  82
  83/*
  84 * The object names in objects array are hashed with this hashtable,
  85 * to help looking up the entry by object name.
  86 * This hashtable is built after all the objects are seen.
  87 */
  88static int *object_ix;
  89static int object_ix_hashsz;
  90
  91/*
  92 * Pack index for existing packs give us easy access to the offsets into
  93 * corresponding pack file where each object's data starts, but the entries
  94 * do not store the size of the compressed representation (uncompressed
  95 * size is easily available by examining the pack entry header).  It is
  96 * also rather expensive to find the sha1 for an object given its offset.
  97 *
  98 * We build a hashtable of existing packs (pack_revindex), and keep reverse
  99 * index here -- pack index file is sorted by object name mapping to offset;
 100 * this pack_revindex[].revindex array is a list of offset/index_nr pairs
 101 * ordered by offset, so if you know the offset of an object, next offset
 102 * is where its packed representation ends and the index_nr can be used to
 103 * get the object sha1 from the main index.
 104 */
 105struct revindex_entry {
 106        off_t offset;
 107        unsigned int nr;
 108};
 109struct pack_revindex {
 110        struct packed_git *p;
 111        struct revindex_entry *revindex;
 112};
 113static struct  pack_revindex *pack_revindex;
 114static int pack_revindex_hashsz;
 115
 116/*
 117 * stats
 118 */
 119static uint32_t written, written_delta;
 120static uint32_t reused, reused_delta;
 121
 122static int pack_revindex_ix(struct packed_git *p)
 123{
 124        unsigned long ui = (unsigned long)p;
 125        int i;
 126
 127        ui = ui ^ (ui >> 16); /* defeat structure alignment */
 128        i = (int)(ui % pack_revindex_hashsz);
 129        while (pack_revindex[i].p) {
 130                if (pack_revindex[i].p == p)
 131                        return i;
 132                if (++i == pack_revindex_hashsz)
 133                        i = 0;
 134        }
 135        return -1 - i;
 136}
 137
 138static void prepare_pack_ix(void)
 139{
 140        int num;
 141        struct packed_git *p;
 142        for (num = 0, p = packed_git; p; p = p->next)
 143                num++;
 144        if (!num)
 145                return;
 146        pack_revindex_hashsz = num * 11;
 147        pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 148        for (p = packed_git; p; p = p->next) {
 149                num = pack_revindex_ix(p);
 150                num = - 1 - num;
 151                pack_revindex[num].p = p;
 152        }
 153        /* revindex elements are lazily initialized */
 154}
 155
 156static int cmp_offset(const void *a_, const void *b_)
 157{
 158        const struct revindex_entry *a = a_;
 159        const struct revindex_entry *b = b_;
 160        return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
 161}
 162
 163/*
 164 * Ordered list of offsets of objects in the pack.
 165 */
 166static void prepare_pack_revindex(struct pack_revindex *rix)
 167{
 168        struct packed_git *p = rix->p;
 169        int num_ent = p->num_objects;
 170        int i;
 171        const char *index = p->index_data;
 172
 173        rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
 174        index += 4 * 256;
 175
 176        if (p->index_version > 1) {
 177                const uint32_t *off_32 =
 178                        (uint32_t *)(index + 8 + p->num_objects * (20 + 4));
 179                const uint32_t *off_64 = off_32 + p->num_objects;
 180                for (i = 0; i < num_ent; i++) {
 181                        uint32_t off = ntohl(*off_32++);
 182                        if (!(off & 0x80000000)) {
 183                                rix->revindex[i].offset = off;
 184                        } else {
 185                                rix->revindex[i].offset =
 186                                        ((uint64_t)ntohl(*off_64++)) << 32;
 187                                rix->revindex[i].offset |=
 188                                        ntohl(*off_64++);
 189                        }
 190                        rix->revindex[i].nr = i;
 191                }
 192        } else {
 193                for (i = 0; i < num_ent; i++) {
 194                        uint32_t hl = *((uint32_t *)(index + 24 * i));
 195                        rix->revindex[i].offset = ntohl(hl);
 196                        rix->revindex[i].nr = i;
 197                }
 198        }
 199
 200        /* This knows the pack format -- the 20-byte trailer
 201         * follows immediately after the last object data.
 202         */
 203        rix->revindex[num_ent].offset = p->pack_size - 20;
 204        rix->revindex[num_ent].nr = -1;
 205        qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
 206}
 207
 208static struct revindex_entry * find_packed_object(struct packed_git *p,
 209                                                  off_t ofs)
 210{
 211        int num;
 212        int lo, hi;
 213        struct pack_revindex *rix;
 214        struct revindex_entry *revindex;
 215        num = pack_revindex_ix(p);
 216        if (num < 0)
 217                die("internal error: pack revindex uninitialized");
 218        rix = &pack_revindex[num];
 219        if (!rix->revindex)
 220                prepare_pack_revindex(rix);
 221        revindex = rix->revindex;
 222        lo = 0;
 223        hi = p->num_objects + 1;
 224        do {
 225                int mi = (lo + hi) / 2;
 226                if (revindex[mi].offset == ofs) {
 227                        return revindex + mi;
 228                }
 229                else if (ofs < revindex[mi].offset)
 230                        hi = mi;
 231                else
 232                        lo = mi + 1;
 233        } while (lo < hi);
 234        die("internal error: pack revindex corrupt");
 235}
 236
 237static const unsigned char *find_packed_object_name(struct packed_git *p,
 238                                                    off_t ofs)
 239{
 240        struct revindex_entry *entry = find_packed_object(p, ofs);
 241        return nth_packed_object_sha1(p, entry->nr);
 242}
 243
 244static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 245{
 246        unsigned long othersize, delta_size;
 247        enum object_type type;
 248        void *otherbuf = read_sha1_file(entry->delta->idx.sha1, &type, &othersize);
 249        void *delta_buf;
 250
 251        if (!otherbuf)
 252                die("unable to read %s", sha1_to_hex(entry->delta->idx.sha1));
 253        delta_buf = diff_delta(otherbuf, othersize,
 254                               buf, size, &delta_size, 0);
 255        if (!delta_buf || delta_size != entry->delta_size)
 256                die("delta size changed");
 257        free(buf);
 258        free(otherbuf);
 259        return delta_buf;
 260}
 261
 262/*
 263 * The per-object header is a pretty dense thing, which is
 264 *  - first byte: low four bits are "size", then three bits of "type",
 265 *    and the high bit is "size continues".
 266 *  - each byte afterwards: low seven bits are size continuation,
 267 *    with the high bit being "size continues"
 268 */
 269static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 270{
 271        int n = 1;
 272        unsigned char c;
 273
 274        if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
 275                die("bad type %d", type);
 276
 277        c = (type << 4) | (size & 15);
 278        size >>= 4;
 279        while (size) {
 280                *hdr++ = c | 0x80;
 281                c = size & 0x7f;
 282                size >>= 7;
 283                n++;
 284        }
 285        *hdr = c;
 286        return n;
 287}
 288
 289/*
 290 * we are going to reuse the existing object data as is.  make
 291 * sure it is not corrupt.
 292 */
 293static int check_pack_inflate(struct packed_git *p,
 294                struct pack_window **w_curs,
 295                off_t offset,
 296                off_t len,
 297                unsigned long expect)
 298{
 299        z_stream stream;
 300        unsigned char fakebuf[4096], *in;
 301        int st;
 302
 303        memset(&stream, 0, sizeof(stream));
 304        inflateInit(&stream);
 305        do {
 306                in = use_pack(p, w_curs, offset, &stream.avail_in);
 307                stream.next_in = in;
 308                stream.next_out = fakebuf;
 309                stream.avail_out = sizeof(fakebuf);
 310                st = inflate(&stream, Z_FINISH);
 311                offset += stream.next_in - in;
 312        } while (st == Z_OK || st == Z_BUF_ERROR);
 313        inflateEnd(&stream);
 314        return (st == Z_STREAM_END &&
 315                stream.total_out == expect &&
 316                stream.total_in == len) ? 0 : -1;
 317}
 318
 319static int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
 320                          off_t offset, off_t len, unsigned int nr)
 321{
 322        const uint32_t *index_crc;
 323        uint32_t data_crc = crc32(0, Z_NULL, 0);
 324
 325        do {
 326                unsigned int avail;
 327                void *data = use_pack(p, w_curs, offset, &avail);
 328                if (avail > len)
 329                        avail = len;
 330                data_crc = crc32(data_crc, data, avail);
 331                offset += avail;
 332                len -= avail;
 333        } while (len);
 334
 335        index_crc = p->index_data;
 336        index_crc += 2 + 256 + p->num_objects * (20/4) + nr;
 337
 338        return data_crc != ntohl(*index_crc);
 339}
 340
 341static void copy_pack_data(struct sha1file *f,
 342                struct packed_git *p,
 343                struct pack_window **w_curs,
 344                off_t offset,
 345                off_t len)
 346{
 347        unsigned char *in;
 348        unsigned int avail;
 349
 350        while (len) {
 351                in = use_pack(p, w_curs, offset, &avail);
 352                if (avail > len)
 353                        avail = (unsigned int)len;
 354                sha1write(f, in, avail);
 355                offset += avail;
 356                len -= avail;
 357        }
 358}
 359
 360static unsigned long write_object(struct sha1file *f,
 361                                  struct object_entry *entry,
 362                                  off_t write_offset)
 363{
 364        unsigned long size;
 365        enum object_type type;
 366        void *buf;
 367        unsigned char header[10];
 368        unsigned char dheader[10];
 369        unsigned hdrlen;
 370        off_t datalen;
 371        enum object_type obj_type;
 372        int to_reuse = 0;
 373        /* write limit if limited packsize and not first object */
 374        unsigned long limit = pack_size_limit && nr_written ?
 375                                pack_size_limit - write_offset : 0;
 376                                /* no if no delta */
 377        int usable_delta =      !entry->delta ? 0 :
 378                                /* yes if unlimited packfile */
 379                                !pack_size_limit ? 1 :
 380                                /* no if base written to previous pack */
 381                                entry->delta->idx.offset == (off_t)-1 ? 0 :
 382                                /* otherwise double-check written to this
 383                                 * pack,  like we do below
 384                                 */
 385                                entry->delta->idx.offset ? 1 : 0;
 386
 387        if (!pack_to_stdout)
 388                crc32_begin(f);
 389
 390        obj_type = entry->type;
 391        if (no_reuse_object)
 392                to_reuse = 0;   /* explicit */
 393        else if (!entry->in_pack)
 394                to_reuse = 0;   /* can't reuse what we don't have */
 395        else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
 396                                /* check_object() decided it for us ... */
 397                to_reuse = usable_delta;
 398                                /* ... but pack split may override that */
 399        else if (obj_type != entry->in_pack_type)
 400                to_reuse = 0;   /* pack has delta which is unusable */
 401        else if (entry->delta)
 402                to_reuse = 0;   /* we want to pack afresh */
 403        else
 404                to_reuse = 1;   /* we have it in-pack undeltified,
 405                                 * and we do not need to deltify it.
 406                                 */
 407
 408        if (!to_reuse) {
 409                z_stream stream;
 410                unsigned long maxsize;
 411                void *out;
 412                if (!usable_delta) {
 413                        buf = read_sha1_file(entry->idx.sha1, &obj_type, &size);
 414                        if (!buf)
 415                                die("unable to read %s", sha1_to_hex(entry->idx.sha1));
 416                } else if (entry->delta_data) {
 417                        size = entry->delta_size;
 418                        buf = entry->delta_data;
 419                        entry->delta_data = NULL;
 420                        obj_type = (allow_ofs_delta && entry->delta->idx.offset) ?
 421                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 422                } else {
 423                        buf = read_sha1_file(entry->idx.sha1, &type, &size);
 424                        if (!buf)
 425                                die("unable to read %s", sha1_to_hex(entry->idx.sha1));
 426                        buf = delta_against(buf, size, entry);
 427                        size = entry->delta_size;
 428                        obj_type = (allow_ofs_delta && entry->delta->idx.offset) ?
 429                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 430                }
 431                /* compress the data to store and put compressed length in datalen */
 432                memset(&stream, 0, sizeof(stream));
 433                deflateInit(&stream, pack_compression_level);
 434                maxsize = deflateBound(&stream, size);
 435                out = xmalloc(maxsize);
 436                /* Compress it */
 437                stream.next_in = buf;
 438                stream.avail_in = size;
 439                stream.next_out = out;
 440                stream.avail_out = maxsize;
 441                while (deflate(&stream, Z_FINISH) == Z_OK)
 442                        /* nothing */;
 443                deflateEnd(&stream);
 444                datalen = stream.total_out;
 445                deflateEnd(&stream);
 446                /*
 447                 * The object header is a byte of 'type' followed by zero or
 448                 * more bytes of length.
 449                 */
 450                hdrlen = encode_header(obj_type, size, header);
 451
 452                if (obj_type == OBJ_OFS_DELTA) {
 453                        /*
 454                         * Deltas with relative base contain an additional
 455                         * encoding of the relative offset for the delta
 456                         * base from this object's position in the pack.
 457                         */
 458                        off_t ofs = entry->idx.offset - entry->delta->idx.offset;
 459                        unsigned pos = sizeof(dheader) - 1;
 460                        dheader[pos] = ofs & 127;
 461                        while (ofs >>= 7)
 462                                dheader[--pos] = 128 | (--ofs & 127);
 463                        if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
 464                                free(out);
 465                                free(buf);
 466                                return 0;
 467                        }
 468                        sha1write(f, header, hdrlen);
 469                        sha1write(f, dheader + pos, sizeof(dheader) - pos);
 470                        hdrlen += sizeof(dheader) - pos;
 471                } else if (obj_type == OBJ_REF_DELTA) {
 472                        /*
 473                         * Deltas with a base reference contain
 474                         * an additional 20 bytes for the base sha1.
 475                         */
 476                        if (limit && hdrlen + 20 + datalen + 20 >= limit) {
 477                                free(out);
 478                                free(buf);
 479                                return 0;
 480                        }
 481                        sha1write(f, header, hdrlen);
 482                        sha1write(f, entry->delta->idx.sha1, 20);
 483                        hdrlen += 20;
 484                } else {
 485                        if (limit && hdrlen + datalen + 20 >= limit) {
 486                                free(out);
 487                                free(buf);
 488                                return 0;
 489                        }
 490                        sha1write(f, header, hdrlen);
 491                }
 492                sha1write(f, out, datalen);
 493                free(out);
 494                free(buf);
 495        }
 496        else {
 497                struct packed_git *p = entry->in_pack;
 498                struct pack_window *w_curs = NULL;
 499                struct revindex_entry *revidx;
 500                off_t offset;
 501
 502                if (entry->delta) {
 503                        obj_type = (allow_ofs_delta && entry->delta->idx.offset) ?
 504                                OBJ_OFS_DELTA : OBJ_REF_DELTA;
 505                        reused_delta++;
 506                }
 507                hdrlen = encode_header(obj_type, entry->size, header);
 508                offset = entry->in_pack_offset;
 509                revidx = find_packed_object(p, offset);
 510                datalen = revidx[1].offset - offset;
 511                if (!pack_to_stdout && p->index_version > 1 &&
 512                    check_pack_crc(p, &w_curs, offset, datalen, revidx->nr))
 513                        die("bad packed object CRC for %s", sha1_to_hex(entry->idx.sha1));
 514                offset += entry->in_pack_header_size;
 515                datalen -= entry->in_pack_header_size;
 516                if (obj_type == OBJ_OFS_DELTA) {
 517                        off_t ofs = entry->idx.offset - entry->delta->idx.offset;
 518                        unsigned pos = sizeof(dheader) - 1;
 519                        dheader[pos] = ofs & 127;
 520                        while (ofs >>= 7)
 521                                dheader[--pos] = 128 | (--ofs & 127);
 522                        if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit)
 523                                return 0;
 524                        sha1write(f, header, hdrlen);
 525                        sha1write(f, dheader + pos, sizeof(dheader) - pos);
 526                        hdrlen += sizeof(dheader) - pos;
 527                } else if (obj_type == OBJ_REF_DELTA) {
 528                        if (limit && hdrlen + 20 + datalen + 20 >= limit)
 529                                return 0;
 530                        sha1write(f, header, hdrlen);
 531                        sha1write(f, entry->delta->idx.sha1, 20);
 532                        hdrlen += 20;
 533                } else {
 534                        if (limit && hdrlen + datalen + 20 >= limit)
 535                                return 0;
 536                        sha1write(f, header, hdrlen);
 537                }
 538
 539                if (!pack_to_stdout && p->index_version == 1 &&
 540                    check_pack_inflate(p, &w_curs, offset, datalen, entry->size))
 541                        die("corrupt packed object for %s", sha1_to_hex(entry->idx.sha1));
 542                copy_pack_data(f, p, &w_curs, offset, datalen);
 543                unuse_pack(&w_curs);
 544                reused++;
 545        }
 546        if (usable_delta)
 547                written_delta++;
 548        written++;
 549        if (!pack_to_stdout)
 550                entry->idx.crc32 = crc32_end(f);
 551        return hdrlen + datalen;
 552}
 553
 554static off_t write_one(struct sha1file *f,
 555                               struct object_entry *e,
 556                               off_t offset)
 557{
 558        unsigned long size;
 559
 560        /* offset is non zero if object is written already. */
 561        if (e->idx.offset || e->preferred_base)
 562                return offset;
 563
 564        /* if we are deltified, write out base object first. */
 565        if (e->delta) {
 566                offset = write_one(f, e->delta, offset);
 567                if (!offset)
 568                        return 0;
 569        }
 570
 571        e->idx.offset = offset;
 572        size = write_object(f, e, offset);
 573        if (!size) {
 574                e->idx.offset = 0;
 575                return 0;
 576        }
 577        written_list[nr_written++] = e;
 578
 579        /* make sure off_t is sufficiently large not to wrap */
 580        if (offset > offset + size)
 581                die("pack too large for current definition of off_t");
 582        return offset + size;
 583}
 584
 585static int open_object_dir_tmp(const char *path)
 586{
 587    snprintf(tmpname, sizeof(tmpname), "%s/%s", get_object_directory(), path);
 588    return xmkstemp(tmpname);
 589}
 590
 591/* forward declaration for write_pack_file */
 592static int adjust_perm(const char *path, mode_t mode);
 593
 594static void write_pack_file(void)
 595{
 596        uint32_t i = 0, j;
 597        struct sha1file *f;
 598        off_t offset, offset_one, last_obj_offset = 0;
 599        struct pack_header hdr;
 600        int do_progress = progress >> pack_to_stdout;
 601        uint32_t nr_remaining = nr_result;
 602
 603        if (do_progress)
 604                start_progress(&progress_state, "Writing %u objects...", "", nr_result);
 605        written_list = xmalloc(nr_objects * sizeof(struct object_entry *));
 606
 607        do {
 608                unsigned char sha1[20];
 609
 610                if (pack_to_stdout) {
 611                        f = sha1fd(1, "<stdout>");
 612                } else {
 613                        int fd = open_object_dir_tmp("tmp_pack_XXXXXX");
 614                        pack_tmp_name = xstrdup(tmpname);
 615                        f = sha1fd(fd, pack_tmp_name);
 616                }
 617
 618                hdr.hdr_signature = htonl(PACK_SIGNATURE);
 619                hdr.hdr_version = htonl(PACK_VERSION);
 620                hdr.hdr_entries = htonl(nr_remaining);
 621                sha1write(f, &hdr, sizeof(hdr));
 622                offset = sizeof(hdr);
 623                nr_written = 0;
 624                for (; i < nr_objects; i++) {
 625                        last_obj_offset = offset;
 626                        offset_one = write_one(f, objects + i, offset);
 627                        if (!offset_one)
 628                                break;
 629                        offset = offset_one;
 630                        if (do_progress)
 631                                display_progress(&progress_state, written);
 632                }
 633
 634                /*
 635                 * Did we write the wrong # entries in the header?
 636                 * If so, rewrite it like in fast-import
 637                 */
 638                if (pack_to_stdout || nr_written == nr_remaining) {
 639                        sha1close(f, sha1, 1);
 640                } else {
 641                        sha1close(f, sha1, 0);
 642                        fixup_pack_header_footer(f->fd, sha1, pack_tmp_name, nr_written);
 643                        close(f->fd);
 644                }
 645
 646                if (!pack_to_stdout) {
 647                        mode_t mode = umask(0);
 648
 649                        umask(mode);
 650                        mode = 0444 & ~mode;
 651
 652                        idx_tmp_name = write_idx_file(NULL,
 653                                (struct pack_idx_entry **) written_list, nr_written, sha1);
 654                        snprintf(tmpname, sizeof(tmpname), "%s-%s.pack",
 655                                 base_name, sha1_to_hex(sha1));
 656                        if (adjust_perm(pack_tmp_name, mode))
 657                                die("unable to make temporary pack file readable: %s",
 658                                    strerror(errno));
 659                        if (rename(pack_tmp_name, tmpname))
 660                                die("unable to rename temporary pack file: %s",
 661                                    strerror(errno));
 662                        snprintf(tmpname, sizeof(tmpname), "%s-%s.idx",
 663                                 base_name, sha1_to_hex(sha1));
 664                        if (adjust_perm(idx_tmp_name, mode))
 665                                die("unable to make temporary index file readable: %s",
 666                                    strerror(errno));
 667                        if (rename(idx_tmp_name, tmpname))
 668                                die("unable to rename temporary index file: %s",
 669                                    strerror(errno));
 670                        puts(sha1_to_hex(sha1));
 671                }
 672
 673                /* mark written objects as written to previous pack */
 674                for (j = 0; j < nr_written; j++) {
 675                        written_list[j]->idx.offset = (off_t)-1;
 676                }
 677                nr_remaining -= nr_written;
 678        } while (nr_remaining && i < nr_objects);
 679
 680        free(written_list);
 681        if (do_progress)
 682                stop_progress(&progress_state);
 683        if (written != nr_result)
 684                die("wrote %u objects while expecting %u", written, nr_result);
 685        /*
 686         * We have scanned through [0 ... i).  Since we have written
 687         * the correct number of objects,  the remaining [i ... nr_objects)
 688         * items must be either already written (due to out-of-order delta base)
 689         * or a preferred base.  Count those which are neither and complain if any.
 690         */
 691        for (j = 0; i < nr_objects; i++) {
 692                struct object_entry *e = objects + i;
 693                j += !e->idx.offset && !e->preferred_base;
 694        }
 695        if (j)
 696                die("wrote %u objects as expected but %u unwritten", written, j);
 697}
 698
 699static int locate_object_entry_hash(const unsigned char *sha1)
 700{
 701        int i;
 702        unsigned int ui;
 703        memcpy(&ui, sha1, sizeof(unsigned int));
 704        i = ui % object_ix_hashsz;
 705        while (0 < object_ix[i]) {
 706                if (!hashcmp(sha1, objects[object_ix[i] - 1].idx.sha1))
 707                        return i;
 708                if (++i == object_ix_hashsz)
 709                        i = 0;
 710        }
 711        return -1 - i;
 712}
 713
 714static struct object_entry *locate_object_entry(const unsigned char *sha1)
 715{
 716        int i;
 717
 718        if (!object_ix_hashsz)
 719                return NULL;
 720
 721        i = locate_object_entry_hash(sha1);
 722        if (0 <= i)
 723                return &objects[object_ix[i]-1];
 724        return NULL;
 725}
 726
 727static void rehash_objects(void)
 728{
 729        uint32_t i;
 730        struct object_entry *oe;
 731
 732        object_ix_hashsz = nr_objects * 3;
 733        if (object_ix_hashsz < 1024)
 734                object_ix_hashsz = 1024;
 735        object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 736        memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 737        for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 738                int ix = locate_object_entry_hash(oe->idx.sha1);
 739                if (0 <= ix)
 740                        continue;
 741                ix = -1 - ix;
 742                object_ix[ix] = i + 1;
 743        }
 744}
 745
 746static unsigned name_hash(const char *name)
 747{
 748        unsigned char c;
 749        unsigned hash = 0;
 750
 751        if (!name)
 752                return 0;
 753
 754        /*
 755         * This effectively just creates a sortable number from the
 756         * last sixteen non-whitespace characters. Last characters
 757         * count "most", so things that end in ".c" sort together.
 758         */
 759        while ((c = *name++) != 0) {
 760                if (isspace(c))
 761                        continue;
 762                hash = (hash >> 2) + (c << 24);
 763        }
 764        return hash;
 765}
 766
 767static void setup_delta_attr_check(struct git_attr_check *check)
 768{
 769        static struct git_attr *attr_delta;
 770
 771        if (!attr_delta)
 772                attr_delta = git_attr("delta", 5);
 773
 774        check[0].attr = attr_delta;
 775}
 776
 777static int no_try_delta(const char *path)
 778{
 779        struct git_attr_check check[1];
 780
 781        setup_delta_attr_check(check);
 782        if (git_checkattr(path, ARRAY_SIZE(check), check))
 783                return 0;
 784        if (ATTR_FALSE(check->value))
 785                return 1;
 786        return 0;
 787}
 788
 789static int add_object_entry(const unsigned char *sha1, enum object_type type,
 790                            const char *name, int exclude)
 791{
 792        struct object_entry *entry;
 793        struct packed_git *p, *found_pack = NULL;
 794        off_t found_offset = 0;
 795        int ix;
 796        unsigned hash = name_hash(name);
 797
 798        ix = nr_objects ? locate_object_entry_hash(sha1) : -1;
 799        if (ix >= 0) {
 800                if (exclude) {
 801                        entry = objects + object_ix[ix] - 1;
 802                        if (!entry->preferred_base)
 803                                nr_result--;
 804                        entry->preferred_base = 1;
 805                }
 806                return 0;
 807        }
 808
 809        for (p = packed_git; p; p = p->next) {
 810                off_t offset = find_pack_entry_one(sha1, p);
 811                if (offset) {
 812                        if (!found_pack) {
 813                                found_offset = offset;
 814                                found_pack = p;
 815                        }
 816                        if (exclude)
 817                                break;
 818                        if (incremental)
 819                                return 0;
 820                        if (local && !p->pack_local)
 821                                return 0;
 822                }
 823        }
 824
 825        if (nr_objects >= nr_alloc) {
 826                nr_alloc = (nr_alloc  + 1024) * 3 / 2;
 827                objects = xrealloc(objects, nr_alloc * sizeof(*entry));
 828        }
 829
 830        entry = objects + nr_objects++;
 831        memset(entry, 0, sizeof(*entry));
 832        hashcpy(entry->idx.sha1, sha1);
 833        entry->hash = hash;
 834        if (type)
 835                entry->type = type;
 836        if (exclude)
 837                entry->preferred_base = 1;
 838        else
 839                nr_result++;
 840        if (found_pack) {
 841                entry->in_pack = found_pack;
 842                entry->in_pack_offset = found_offset;
 843        }
 844
 845        if (object_ix_hashsz * 3 <= nr_objects * 4)
 846                rehash_objects();
 847        else
 848                object_ix[-1 - ix] = nr_objects;
 849
 850        if (progress)
 851                display_progress(&progress_state, nr_objects);
 852
 853        if (name && no_try_delta(name))
 854                entry->no_try_delta = 1;
 855
 856        return 1;
 857}
 858
 859struct pbase_tree_cache {
 860        unsigned char sha1[20];
 861        int ref;
 862        int temporary;
 863        void *tree_data;
 864        unsigned long tree_size;
 865};
 866
 867static struct pbase_tree_cache *(pbase_tree_cache[256]);
 868static int pbase_tree_cache_ix(const unsigned char *sha1)
 869{
 870        return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 871}
 872static int pbase_tree_cache_ix_incr(int ix)
 873{
 874        return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 875}
 876
 877static struct pbase_tree {
 878        struct pbase_tree *next;
 879        /* This is a phony "cache" entry; we are not
 880         * going to evict it nor find it through _get()
 881         * mechanism -- this is for the toplevel node that
 882         * would almost always change with any commit.
 883         */
 884        struct pbase_tree_cache pcache;
 885} *pbase_tree;
 886
 887static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 888{
 889        struct pbase_tree_cache *ent, *nent;
 890        void *data;
 891        unsigned long size;
 892        enum object_type type;
 893        int neigh;
 894        int my_ix = pbase_tree_cache_ix(sha1);
 895        int available_ix = -1;
 896
 897        /* pbase-tree-cache acts as a limited hashtable.
 898         * your object will be found at your index or within a few
 899         * slots after that slot if it is cached.
 900         */
 901        for (neigh = 0; neigh < 8; neigh++) {
 902                ent = pbase_tree_cache[my_ix];
 903                if (ent && !hashcmp(ent->sha1, sha1)) {
 904                        ent->ref++;
 905                        return ent;
 906                }
 907                else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 908                         ((0 <= available_ix) &&
 909                          (!ent && pbase_tree_cache[available_ix])))
 910                        available_ix = my_ix;
 911                if (!ent)
 912                        break;
 913                my_ix = pbase_tree_cache_ix_incr(my_ix);
 914        }
 915
 916        /* Did not find one.  Either we got a bogus request or
 917         * we need to read and perhaps cache.
 918         */
 919        data = read_sha1_file(sha1, &type, &size);
 920        if (!data)
 921                return NULL;
 922        if (type != OBJ_TREE) {
 923                free(data);
 924                return NULL;
 925        }
 926
 927        /* We need to either cache or return a throwaway copy */
 928
 929        if (available_ix < 0)
 930                ent = NULL;
 931        else {
 932                ent = pbase_tree_cache[available_ix];
 933                my_ix = available_ix;
 934        }
 935
 936        if (!ent) {
 937                nent = xmalloc(sizeof(*nent));
 938                nent->temporary = (available_ix < 0);
 939        }
 940        else {
 941                /* evict and reuse */
 942                free(ent->tree_data);
 943                nent = ent;
 944        }
 945        hashcpy(nent->sha1, sha1);
 946        nent->tree_data = data;
 947        nent->tree_size = size;
 948        nent->ref = 1;
 949        if (!nent->temporary)
 950                pbase_tree_cache[my_ix] = nent;
 951        return nent;
 952}
 953
 954static void pbase_tree_put(struct pbase_tree_cache *cache)
 955{
 956        if (!cache->temporary) {
 957                cache->ref--;
 958                return;
 959        }
 960        free(cache->tree_data);
 961        free(cache);
 962}
 963
 964static int name_cmp_len(const char *name)
 965{
 966        int i;
 967        for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 968                ;
 969        return i;
 970}
 971
 972static void add_pbase_object(struct tree_desc *tree,
 973                             const char *name,
 974                             int cmplen,
 975                             const char *fullname)
 976{
 977        struct name_entry entry;
 978        int cmp;
 979
 980        while (tree_entry(tree,&entry)) {
 981                if (S_ISGITLINK(entry.mode))
 982                        continue;
 983                cmp = tree_entry_len(entry.path, entry.sha1) != cmplen ? 1 :
 984                      memcmp(name, entry.path, cmplen);
 985                if (cmp > 0)
 986                        continue;
 987                if (cmp < 0)
 988                        return;
 989                if (name[cmplen] != '/') {
 990                        add_object_entry(entry.sha1,
 991                                         S_ISDIR(entry.mode) ? OBJ_TREE : OBJ_BLOB,
 992                                         fullname, 1);
 993                        return;
 994                }
 995                if (S_ISDIR(entry.mode)) {
 996                        struct tree_desc sub;
 997                        struct pbase_tree_cache *tree;
 998                        const char *down = name+cmplen+1;
 999                        int downlen = name_cmp_len(down);
1000
1001                        tree = pbase_tree_get(entry.sha1);
1002                        if (!tree)
1003                                return;
1004                        init_tree_desc(&sub, tree->tree_data, tree->tree_size);
1005
1006                        add_pbase_object(&sub, down, downlen, fullname);
1007                        pbase_tree_put(tree);
1008                }
1009        }
1010}
1011
1012static unsigned *done_pbase_paths;
1013static int done_pbase_paths_num;
1014static int done_pbase_paths_alloc;
1015static int done_pbase_path_pos(unsigned hash)
1016{
1017        int lo = 0;
1018        int hi = done_pbase_paths_num;
1019        while (lo < hi) {
1020                int mi = (hi + lo) / 2;
1021                if (done_pbase_paths[mi] == hash)
1022                        return mi;
1023                if (done_pbase_paths[mi] < hash)
1024                        hi = mi;
1025                else
1026                        lo = mi + 1;
1027        }
1028        return -lo-1;
1029}
1030
1031static int check_pbase_path(unsigned hash)
1032{
1033        int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
1034        if (0 <= pos)
1035                return 1;
1036        pos = -pos - 1;
1037        if (done_pbase_paths_alloc <= done_pbase_paths_num) {
1038                done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
1039                done_pbase_paths = xrealloc(done_pbase_paths,
1040                                            done_pbase_paths_alloc *
1041                                            sizeof(unsigned));
1042        }
1043        done_pbase_paths_num++;
1044        if (pos < done_pbase_paths_num)
1045                memmove(done_pbase_paths + pos + 1,
1046                        done_pbase_paths + pos,
1047                        (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
1048        done_pbase_paths[pos] = hash;
1049        return 0;
1050}
1051
1052static void add_preferred_base_object(const char *name)
1053{
1054        struct pbase_tree *it;
1055        int cmplen;
1056        unsigned hash = name_hash(name);
1057
1058        if (!num_preferred_base || check_pbase_path(hash))
1059                return;
1060
1061        cmplen = name_cmp_len(name);
1062        for (it = pbase_tree; it; it = it->next) {
1063                if (cmplen == 0) {
1064                        add_object_entry(it->pcache.sha1, OBJ_TREE, NULL, 1);
1065                }
1066                else {
1067                        struct tree_desc tree;
1068                        init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
1069                        add_pbase_object(&tree, name, cmplen, name);
1070                }
1071        }
1072}
1073
1074static void add_preferred_base(unsigned char *sha1)
1075{
1076        struct pbase_tree *it;
1077        void *data;
1078        unsigned long size;
1079        unsigned char tree_sha1[20];
1080
1081        if (window <= num_preferred_base++)
1082                return;
1083
1084        data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
1085        if (!data)
1086                return;
1087
1088        for (it = pbase_tree; it; it = it->next) {
1089                if (!hashcmp(it->pcache.sha1, tree_sha1)) {
1090                        free(data);
1091                        return;
1092                }
1093        }
1094
1095        it = xcalloc(1, sizeof(*it));
1096        it->next = pbase_tree;
1097        pbase_tree = it;
1098
1099        hashcpy(it->pcache.sha1, tree_sha1);
1100        it->pcache.tree_data = data;
1101        it->pcache.tree_size = size;
1102}
1103
1104static void check_object(struct object_entry *entry)
1105{
1106        if (entry->in_pack) {
1107                struct packed_git *p = entry->in_pack;
1108                struct pack_window *w_curs = NULL;
1109                const unsigned char *base_ref = NULL;
1110                struct object_entry *base_entry;
1111                unsigned long used, used_0;
1112                unsigned int avail;
1113                off_t ofs;
1114                unsigned char *buf, c;
1115
1116                buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
1117
1118                /*
1119                 * We want in_pack_type even if we do not reuse delta
1120                 * since non-delta representations could still be reused.
1121                 */
1122                used = unpack_object_header_gently(buf, avail,
1123                                                   &entry->in_pack_type,
1124                                                   &entry->size);
1125
1126                /*
1127                 * Determine if this is a delta and if so whether we can
1128                 * reuse it or not.  Otherwise let's find out as cheaply as
1129                 * possible what the actual type and size for this object is.
1130                 */
1131                switch (entry->in_pack_type) {
1132                default:
1133                        /* Not a delta hence we've already got all we need. */
1134                        entry->type = entry->in_pack_type;
1135                        entry->in_pack_header_size = used;
1136                        unuse_pack(&w_curs);
1137                        return;
1138                case OBJ_REF_DELTA:
1139                        if (!no_reuse_delta && !entry->preferred_base)
1140                                base_ref = use_pack(p, &w_curs,
1141                                                entry->in_pack_offset + used, NULL);
1142                        entry->in_pack_header_size = used + 20;
1143                        break;
1144                case OBJ_OFS_DELTA:
1145                        buf = use_pack(p, &w_curs,
1146                                       entry->in_pack_offset + used, NULL);
1147                        used_0 = 0;
1148                        c = buf[used_0++];
1149                        ofs = c & 127;
1150                        while (c & 128) {
1151                                ofs += 1;
1152                                if (!ofs || MSB(ofs, 7))
1153                                        die("delta base offset overflow in pack for %s",
1154                                            sha1_to_hex(entry->idx.sha1));
1155                                c = buf[used_0++];
1156                                ofs = (ofs << 7) + (c & 127);
1157                        }
1158                        if (ofs >= entry->in_pack_offset)
1159                                die("delta base offset out of bound for %s",
1160                                    sha1_to_hex(entry->idx.sha1));
1161                        ofs = entry->in_pack_offset - ofs;
1162                        if (!no_reuse_delta && !entry->preferred_base)
1163                                base_ref = find_packed_object_name(p, ofs);
1164                        entry->in_pack_header_size = used + used_0;
1165                        break;
1166                }
1167
1168                if (base_ref && (base_entry = locate_object_entry(base_ref))) {
1169                        /*
1170                         * If base_ref was set above that means we wish to
1171                         * reuse delta data, and we even found that base
1172                         * in the list of objects we want to pack. Goodie!
1173                         *
1174                         * Depth value does not matter - find_deltas() will
1175                         * never consider reused delta as the base object to
1176                         * deltify other objects against, in order to avoid
1177                         * circular deltas.
1178                         */
1179                        entry->type = entry->in_pack_type;
1180                        entry->delta = base_entry;
1181                        entry->delta_sibling = base_entry->delta_child;
1182                        base_entry->delta_child = entry;
1183                        unuse_pack(&w_curs);
1184                        return;
1185                }
1186
1187                if (entry->type) {
1188                        /*
1189                         * This must be a delta and we already know what the
1190                         * final object type is.  Let's extract the actual
1191                         * object size from the delta header.
1192                         */
1193                        entry->size = get_size_from_delta(p, &w_curs,
1194                                        entry->in_pack_offset + entry->in_pack_header_size);
1195                        unuse_pack(&w_curs);
1196                        return;
1197                }
1198
1199                /*
1200                 * No choice but to fall back to the recursive delta walk
1201                 * with sha1_object_info() to find about the object type
1202                 * at this point...
1203                 */
1204                unuse_pack(&w_curs);
1205        }
1206
1207        entry->type = sha1_object_info(entry->idx.sha1, &entry->size);
1208        if (entry->type < 0)
1209                die("unable to get type of object %s",
1210                    sha1_to_hex(entry->idx.sha1));
1211}
1212
1213static int pack_offset_sort(const void *_a, const void *_b)
1214{
1215        const struct object_entry *a = *(struct object_entry **)_a;
1216        const struct object_entry *b = *(struct object_entry **)_b;
1217
1218        /* avoid filesystem trashing with loose objects */
1219        if (!a->in_pack && !b->in_pack)
1220                return hashcmp(a->idx.sha1, b->idx.sha1);
1221
1222        if (a->in_pack < b->in_pack)
1223                return -1;
1224        if (a->in_pack > b->in_pack)
1225                return 1;
1226        return a->in_pack_offset < b->in_pack_offset ? -1 :
1227                        (a->in_pack_offset > b->in_pack_offset);
1228}
1229
1230static void get_object_details(void)
1231{
1232        uint32_t i;
1233        struct object_entry **sorted_by_offset;
1234
1235        sorted_by_offset = xcalloc(nr_objects, sizeof(struct object_entry *));
1236        for (i = 0; i < nr_objects; i++)
1237                sorted_by_offset[i] = objects + i;
1238        qsort(sorted_by_offset, nr_objects, sizeof(*sorted_by_offset), pack_offset_sort);
1239
1240        prepare_pack_ix();
1241        for (i = 0; i < nr_objects; i++)
1242                check_object(sorted_by_offset[i]);
1243        free(sorted_by_offset);
1244}
1245
1246static int type_size_sort(const void *_a, const void *_b)
1247{
1248        const struct object_entry *a = *(struct object_entry **)_a;
1249        const struct object_entry *b = *(struct object_entry **)_b;
1250
1251        if (a->type < b->type)
1252                return -1;
1253        if (a->type > b->type)
1254                return 1;
1255        if (a->hash < b->hash)
1256                return -1;
1257        if (a->hash > b->hash)
1258                return 1;
1259        if (a->preferred_base < b->preferred_base)
1260                return -1;
1261        if (a->preferred_base > b->preferred_base)
1262                return 1;
1263        if (a->size < b->size)
1264                return -1;
1265        if (a->size > b->size)
1266                return 1;
1267        return a > b ? -1 : (a < b);  /* newest last */
1268}
1269
1270struct unpacked {
1271        struct object_entry *entry;
1272        void *data;
1273        struct delta_index *index;
1274        unsigned depth;
1275};
1276
1277static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
1278                           unsigned long delta_size)
1279{
1280        if (max_delta_cache_size && delta_cache_size + delta_size > max_delta_cache_size)
1281                return 0;
1282
1283        if (delta_size < cache_max_small_delta_size)
1284                return 1;
1285
1286        /* cache delta, if objects are large enough compared to delta size */
1287        if ((src_size >> 20) + (trg_size >> 21) > (delta_size >> 10))
1288                return 1;
1289
1290        return 0;
1291}
1292
1293/*
1294 * We search for deltas _backwards_ in a list sorted by type and
1295 * by size, so that we see progressively smaller and smaller files.
1296 * That's because we prefer deltas to be from the bigger file
1297 * to the smaller - deletes are potentially cheaper, but perhaps
1298 * more importantly, the bigger file is likely the more recent
1299 * one.
1300 */
1301static int try_delta(struct unpacked *trg, struct unpacked *src,
1302                     unsigned max_depth, unsigned long *mem_usage)
1303{
1304        struct object_entry *trg_entry = trg->entry;
1305        struct object_entry *src_entry = src->entry;
1306        unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
1307        unsigned ref_depth;
1308        enum object_type type;
1309        void *delta_buf;
1310
1311        /* Don't bother doing diffs between different types */
1312        if (trg_entry->type != src_entry->type)
1313                return -1;
1314
1315        /*
1316         * We do not bother to try a delta that we discarded
1317         * on an earlier try, but only when reusing delta data.
1318         */
1319        if (!no_reuse_delta && trg_entry->in_pack &&
1320            trg_entry->in_pack == src_entry->in_pack &&
1321            trg_entry->in_pack_type != OBJ_REF_DELTA &&
1322            trg_entry->in_pack_type != OBJ_OFS_DELTA)
1323                return 0;
1324
1325        /* Let's not bust the allowed depth. */
1326        if (src->depth >= max_depth)
1327                return 0;
1328
1329        /* Now some size filtering heuristics. */
1330        trg_size = trg_entry->size;
1331        if (!trg_entry->delta) {
1332                max_size = trg_size/2 - 20;
1333                ref_depth = 1;
1334        } else {
1335                max_size = trg_entry->delta_size;
1336                ref_depth = trg->depth;
1337        }
1338        max_size = max_size * (max_depth - src->depth) /
1339                                                (max_depth - ref_depth + 1);
1340        if (max_size == 0)
1341                return 0;
1342        src_size = src_entry->size;
1343        sizediff = src_size < trg_size ? trg_size - src_size : 0;
1344        if (sizediff >= max_size)
1345                return 0;
1346        if (trg_size < src_size / 32)
1347                return 0;
1348
1349        /* Load data if not already done */
1350        if (!trg->data) {
1351                trg->data = read_sha1_file(trg_entry->idx.sha1, &type, &sz);
1352                if (!trg->data)
1353                        die("object %s cannot be read",
1354                            sha1_to_hex(trg_entry->idx.sha1));
1355                if (sz != trg_size)
1356                        die("object %s inconsistent object length (%lu vs %lu)",
1357                            sha1_to_hex(trg_entry->idx.sha1), sz, trg_size);
1358                *mem_usage += sz;
1359        }
1360        if (!src->data) {
1361                src->data = read_sha1_file(src_entry->idx.sha1, &type, &sz);
1362                if (!src->data)
1363                        die("object %s cannot be read",
1364                            sha1_to_hex(src_entry->idx.sha1));
1365                if (sz != src_size)
1366                        die("object %s inconsistent object length (%lu vs %lu)",
1367                            sha1_to_hex(src_entry->idx.sha1), sz, src_size);
1368                *mem_usage += sz;
1369        }
1370        if (!src->index) {
1371                src->index = create_delta_index(src->data, src_size);
1372                if (!src->index) {
1373                        static int warned = 0;
1374                        if (!warned++)
1375                                warning("suboptimal pack - out of memory");
1376                        return 0;
1377                }
1378                *mem_usage += sizeof_delta_index(src->index);
1379        }
1380
1381        delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1382        if (!delta_buf)
1383                return 0;
1384
1385        if (trg_entry->delta) {
1386                /* Prefer only shallower same-sized deltas. */
1387                if (delta_size == trg_entry->delta_size &&
1388                    src->depth + 1 >= trg->depth) {
1389                        free(delta_buf);
1390                        return 0;
1391                }
1392        }
1393
1394        trg_entry->delta = src_entry;
1395        trg_entry->delta_size = delta_size;
1396        trg->depth = src->depth + 1;
1397
1398        if (trg_entry->delta_data) {
1399                delta_cache_size -= trg_entry->delta_size;
1400                free(trg_entry->delta_data);
1401                trg_entry->delta_data = NULL;
1402        }
1403
1404        if (delta_cacheable(src_size, trg_size, delta_size)) {
1405                trg_entry->delta_data = xrealloc(delta_buf, delta_size);
1406                delta_cache_size += trg_entry->delta_size;
1407        } else
1408                free(delta_buf);
1409        return 1;
1410}
1411
1412static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
1413{
1414        struct object_entry *child = me->delta_child;
1415        unsigned int m = n;
1416        while (child) {
1417                unsigned int c = check_delta_limit(child, n + 1);
1418                if (m < c)
1419                        m = c;
1420                child = child->delta_sibling;
1421        }
1422        return m;
1423}
1424
1425static unsigned long free_unpacked(struct unpacked *n)
1426{
1427        unsigned long freed_mem = sizeof_delta_index(n->index);
1428        free_delta_index(n->index);
1429        n->index = NULL;
1430        if (n->data) {
1431                freed_mem += n->entry->size;
1432                free(n->data);
1433                n->data = NULL;
1434        }
1435        n->entry = NULL;
1436        n->depth = 0;
1437        return freed_mem;
1438}
1439
1440static void find_deltas(struct object_entry **list, unsigned list_size,
1441                        int window, int depth, unsigned *processed)
1442{
1443        uint32_t i = list_size, idx = 0, count = 0;
1444        unsigned int array_size = window * sizeof(struct unpacked);
1445        struct unpacked *array;
1446        unsigned long mem_usage = 0;
1447
1448        array = xmalloc(array_size);
1449        memset(array, 0, array_size);
1450
1451        do {
1452                struct object_entry *entry = list[--i];
1453                struct unpacked *n = array + idx;
1454                int j, max_depth, best_base = -1;
1455
1456                mem_usage -= free_unpacked(n);
1457                n->entry = entry;
1458
1459                while (window_memory_limit &&
1460                       mem_usage > window_memory_limit &&
1461                       count > 1) {
1462                        uint32_t tail = (idx + window - count) % window;
1463                        mem_usage -= free_unpacked(array + tail);
1464                        count--;
1465                }
1466
1467                /* We do not compute delta to *create* objects we are not
1468                 * going to pack.
1469                 */
1470                if (entry->preferred_base)
1471                        goto next;
1472
1473                (*processed)++;
1474                if (progress)
1475                        display_progress(&progress_state, *processed);
1476
1477                /*
1478                 * If the current object is at pack edge, take the depth the
1479                 * objects that depend on the current object into account
1480                 * otherwise they would become too deep.
1481                 */
1482                max_depth = depth;
1483                if (entry->delta_child) {
1484                        max_depth -= check_delta_limit(entry, 0);
1485                        if (max_depth <= 0)
1486                                goto next;
1487                }
1488
1489                j = window;
1490                while (--j > 0) {
1491                        int ret;
1492                        uint32_t other_idx = idx + j;
1493                        struct unpacked *m;
1494                        if (other_idx >= window)
1495                                other_idx -= window;
1496                        m = array + other_idx;
1497                        if (!m->entry)
1498                                break;
1499                        ret = try_delta(n, m, max_depth, &mem_usage);
1500                        if (ret < 0)
1501                                break;
1502                        else if (ret > 0)
1503                                best_base = other_idx;
1504                }
1505
1506                /* if we made n a delta, and if n is already at max
1507                 * depth, leaving it in the window is pointless.  we
1508                 * should evict it first.
1509                 */
1510                if (entry->delta && depth <= n->depth)
1511                        continue;
1512
1513                /*
1514                 * Move the best delta base up in the window, after the
1515                 * currently deltified object, to keep it longer.  It will
1516                 * be the first base object to be attempted next.
1517                 */
1518                if (entry->delta) {
1519                        struct unpacked swap = array[best_base];
1520                        int dist = (window + idx - best_base) % window;
1521                        int dst = best_base;
1522                        while (dist--) {
1523                                int src = (dst + 1) % window;
1524                                array[dst] = array[src];
1525                                dst = src;
1526                        }
1527                        array[dst] = swap;
1528                }
1529
1530                next:
1531                idx++;
1532                if (count + 1 < window)
1533                        count++;
1534                if (idx >= window)
1535                        idx = 0;
1536        } while (i > 0);
1537
1538        for (i = 0; i < window; ++i) {
1539                free_delta_index(array[i].index);
1540                free(array[i].data);
1541        }
1542        free(array);
1543}
1544
1545static void prepare_pack(int window, int depth)
1546{
1547        struct object_entry **delta_list;
1548        uint32_t i, n, nr_deltas;
1549
1550        get_object_details();
1551
1552        if (!nr_objects || !window || !depth)
1553                return;
1554
1555        delta_list = xmalloc(nr_objects * sizeof(*delta_list));
1556        nr_deltas = n = 0;
1557
1558        for (i = 0; i < nr_objects; i++) {
1559                struct object_entry *entry = objects + i;
1560
1561                if (entry->delta)
1562                        /* This happens if we decided to reuse existing
1563                         * delta from a pack.  "!no_reuse_delta &&" is implied.
1564                         */
1565                        continue;
1566
1567                if (entry->size < 50)
1568                        continue;
1569
1570                if (entry->no_try_delta)
1571                        continue;
1572
1573                if (!entry->preferred_base)
1574                        nr_deltas++;
1575
1576                delta_list[n++] = entry;
1577        }
1578
1579        if (nr_deltas) {
1580                unsigned nr_done = 0;
1581                if (progress)
1582                        start_progress(&progress_state,
1583                                       "Deltifying %u objects...", "",
1584                                       nr_deltas);
1585                qsort(delta_list, n, sizeof(*delta_list), type_size_sort);
1586                find_deltas(delta_list, n, window+1, depth, &nr_done);
1587                if (progress)
1588                        stop_progress(&progress_state);
1589                if (nr_done != nr_deltas)
1590                        die("inconsistency with delta count");
1591        }
1592        free(delta_list);
1593}
1594
1595static int git_pack_config(const char *k, const char *v)
1596{
1597        if(!strcmp(k, "pack.window")) {
1598                window = git_config_int(k, v);
1599                return 0;
1600        }
1601        if (!strcmp(k, "pack.windowmemory")) {
1602                window_memory_limit = git_config_ulong(k, v);
1603                return 0;
1604        }
1605        if (!strcmp(k, "pack.depth")) {
1606                depth = git_config_int(k, v);
1607                return 0;
1608        }
1609        if (!strcmp(k, "pack.compression")) {
1610                int level = git_config_int(k, v);
1611                if (level == -1)
1612                        level = Z_DEFAULT_COMPRESSION;
1613                else if (level < 0 || level > Z_BEST_COMPRESSION)
1614                        die("bad pack compression level %d", level);
1615                pack_compression_level = level;
1616                pack_compression_seen = 1;
1617                return 0;
1618        }
1619        if (!strcmp(k, "pack.deltacachesize")) {
1620                max_delta_cache_size = git_config_int(k, v);
1621                return 0;
1622        }
1623        if (!strcmp(k, "pack.deltacachelimit")) {
1624                cache_max_small_delta_size = git_config_int(k, v);
1625                return 0;
1626        }
1627        return git_default_config(k, v);
1628}
1629
1630static void read_object_list_from_stdin(void)
1631{
1632        char line[40 + 1 + PATH_MAX + 2];
1633        unsigned char sha1[20];
1634
1635        for (;;) {
1636                if (!fgets(line, sizeof(line), stdin)) {
1637                        if (feof(stdin))
1638                                break;
1639                        if (!ferror(stdin))
1640                                die("fgets returned NULL, not EOF, not error!");
1641                        if (errno != EINTR)
1642                                die("fgets: %s", strerror(errno));
1643                        clearerr(stdin);
1644                        continue;
1645                }
1646                if (line[0] == '-') {
1647                        if (get_sha1_hex(line+1, sha1))
1648                                die("expected edge sha1, got garbage:\n %s",
1649                                    line);
1650                        add_preferred_base(sha1);
1651                        continue;
1652                }
1653                if (get_sha1_hex(line, sha1))
1654                        die("expected sha1, got garbage:\n %s", line);
1655
1656                add_preferred_base_object(line+41);
1657                add_object_entry(sha1, 0, line+41, 0);
1658        }
1659}
1660
1661static void show_commit(struct commit *commit)
1662{
1663        add_object_entry(commit->object.sha1, OBJ_COMMIT, NULL, 0);
1664}
1665
1666static void show_object(struct object_array_entry *p)
1667{
1668        add_preferred_base_object(p->name);
1669        add_object_entry(p->item->sha1, p->item->type, p->name, 0);
1670}
1671
1672static void show_edge(struct commit *commit)
1673{
1674        add_preferred_base(commit->object.sha1);
1675}
1676
1677static void get_object_list(int ac, const char **av)
1678{
1679        struct rev_info revs;
1680        char line[1000];
1681        int flags = 0;
1682
1683        init_revisions(&revs, NULL);
1684        save_commit_buffer = 0;
1685        track_object_refs = 0;
1686        setup_revisions(ac, av, &revs, NULL);
1687
1688        while (fgets(line, sizeof(line), stdin) != NULL) {
1689                int len = strlen(line);
1690                if (line[len - 1] == '\n')
1691                        line[--len] = 0;
1692                if (!len)
1693                        break;
1694                if (*line == '-') {
1695                        if (!strcmp(line, "--not")) {
1696                                flags ^= UNINTERESTING;
1697                                continue;
1698                        }
1699                        die("not a rev '%s'", line);
1700                }
1701                if (handle_revision_arg(line, &revs, flags, 1))
1702                        die("bad revision '%s'", line);
1703        }
1704
1705        prepare_revision_walk(&revs);
1706        mark_edges_uninteresting(revs.commits, &revs, show_edge);
1707        traverse_commit_list(&revs, show_commit, show_object);
1708}
1709
1710static int adjust_perm(const char *path, mode_t mode)
1711{
1712        if (chmod(path, mode))
1713                return -1;
1714        return adjust_shared_perm(path);
1715}
1716
1717int cmd_pack_objects(int argc, const char **argv, const char *prefix)
1718{
1719        int use_internal_rev_list = 0;
1720        int thin = 0;
1721        uint32_t i;
1722        const char **rp_av;
1723        int rp_ac_alloc = 64;
1724        int rp_ac;
1725
1726        rp_av = xcalloc(rp_ac_alloc, sizeof(*rp_av));
1727
1728        rp_av[0] = "pack-objects";
1729        rp_av[1] = "--objects"; /* --thin will make it --objects-edge */
1730        rp_ac = 2;
1731
1732        git_config(git_pack_config);
1733        if (!pack_compression_seen && core_compression_seen)
1734                pack_compression_level = core_compression_level;
1735
1736        progress = isatty(2);
1737        for (i = 1; i < argc; i++) {
1738                const char *arg = argv[i];
1739
1740                if (*arg != '-')
1741                        break;
1742
1743                if (!strcmp("--non-empty", arg)) {
1744                        non_empty = 1;
1745                        continue;
1746                }
1747                if (!strcmp("--local", arg)) {
1748                        local = 1;
1749                        continue;
1750                }
1751                if (!strcmp("--incremental", arg)) {
1752                        incremental = 1;
1753                        continue;
1754                }
1755                if (!prefixcmp(arg, "--compression=")) {
1756                        char *end;
1757                        int level = strtoul(arg+14, &end, 0);
1758                        if (!arg[14] || *end)
1759                                usage(pack_usage);
1760                        if (level == -1)
1761                                level = Z_DEFAULT_COMPRESSION;
1762                        else if (level < 0 || level > Z_BEST_COMPRESSION)
1763                                die("bad pack compression level %d", level);
1764                        pack_compression_level = level;
1765                        continue;
1766                }
1767                if (!prefixcmp(arg, "--max-pack-size=")) {
1768                        char *end;
1769                        pack_size_limit = strtoul(arg+16, &end, 0) * 1024 * 1024;
1770                        if (!arg[16] || *end)
1771                                usage(pack_usage);
1772                        continue;
1773                }
1774                if (!prefixcmp(arg, "--window=")) {
1775                        char *end;
1776                        window = strtoul(arg+9, &end, 0);
1777                        if (!arg[9] || *end)
1778                                usage(pack_usage);
1779                        continue;
1780                }
1781                if (!prefixcmp(arg, "--window-memory=")) {
1782                        if (!git_parse_ulong(arg+16, &window_memory_limit))
1783                                usage(pack_usage);
1784                        continue;
1785                }
1786                if (!prefixcmp(arg, "--depth=")) {
1787                        char *end;
1788                        depth = strtoul(arg+8, &end, 0);
1789                        if (!arg[8] || *end)
1790                                usage(pack_usage);
1791                        continue;
1792                }
1793                if (!strcmp("--progress", arg)) {
1794                        progress = 1;
1795                        continue;
1796                }
1797                if (!strcmp("--all-progress", arg)) {
1798                        progress = 2;
1799                        continue;
1800                }
1801                if (!strcmp("-q", arg)) {
1802                        progress = 0;
1803                        continue;
1804                }
1805                if (!strcmp("--no-reuse-delta", arg)) {
1806                        no_reuse_delta = 1;
1807                        continue;
1808                }
1809                if (!strcmp("--no-reuse-object", arg)) {
1810                        no_reuse_object = no_reuse_delta = 1;
1811                        continue;
1812                }
1813                if (!strcmp("--delta-base-offset", arg)) {
1814                        allow_ofs_delta = 1;
1815                        continue;
1816                }
1817                if (!strcmp("--stdout", arg)) {
1818                        pack_to_stdout = 1;
1819                        continue;
1820                }
1821                if (!strcmp("--revs", arg)) {
1822                        use_internal_rev_list = 1;
1823                        continue;
1824                }
1825                if (!strcmp("--unpacked", arg) ||
1826                    !prefixcmp(arg, "--unpacked=") ||
1827                    !strcmp("--reflog", arg) ||
1828                    !strcmp("--all", arg)) {
1829                        use_internal_rev_list = 1;
1830                        if (rp_ac >= rp_ac_alloc - 1) {
1831                                rp_ac_alloc = alloc_nr(rp_ac_alloc);
1832                                rp_av = xrealloc(rp_av,
1833                                                 rp_ac_alloc * sizeof(*rp_av));
1834                        }
1835                        rp_av[rp_ac++] = arg;
1836                        continue;
1837                }
1838                if (!strcmp("--thin", arg)) {
1839                        use_internal_rev_list = 1;
1840                        thin = 1;
1841                        rp_av[1] = "--objects-edge";
1842                        continue;
1843                }
1844                if (!prefixcmp(arg, "--index-version=")) {
1845                        char *c;
1846                        pack_idx_default_version = strtoul(arg + 16, &c, 10);
1847                        if (pack_idx_default_version > 2)
1848                                die("bad %s", arg);
1849                        if (*c == ',')
1850                                pack_idx_off32_limit = strtoul(c+1, &c, 0);
1851                        if (*c || pack_idx_off32_limit & 0x80000000)
1852                                die("bad %s", arg);
1853                        continue;
1854                }
1855                usage(pack_usage);
1856        }
1857
1858        /* Traditionally "pack-objects [options] base extra" failed;
1859         * we would however want to take refs parameter that would
1860         * have been given to upstream rev-list ourselves, which means
1861         * we somehow want to say what the base name is.  So the
1862         * syntax would be:
1863         *
1864         * pack-objects [options] base <refs...>
1865         *
1866         * in other words, we would treat the first non-option as the
1867         * base_name and send everything else to the internal revision
1868         * walker.
1869         */
1870
1871        if (!pack_to_stdout)
1872                base_name = argv[i++];
1873
1874        if (pack_to_stdout != !base_name)
1875                usage(pack_usage);
1876
1877        if (pack_to_stdout && pack_size_limit)
1878                die("--max-pack-size cannot be used to build a pack for transfer.");
1879
1880        if (!pack_to_stdout && thin)
1881                die("--thin cannot be used to build an indexable pack.");
1882
1883        prepare_packed_git();
1884
1885        if (progress)
1886                start_progress(&progress_state, "Generating pack...",
1887                               "Counting objects: ", 0);
1888        if (!use_internal_rev_list)
1889                read_object_list_from_stdin();
1890        else {
1891                rp_av[rp_ac] = NULL;
1892                get_object_list(rp_ac, rp_av);
1893        }
1894        if (progress) {
1895                stop_progress(&progress_state);
1896                fprintf(stderr, "Done counting %u objects.\n", nr_objects);
1897        }
1898
1899        if (non_empty && !nr_result)
1900                return 0;
1901        if (progress && (nr_objects != nr_result))
1902                fprintf(stderr, "Result has %u objects.\n", nr_result);
1903        if (nr_result)
1904                prepare_pack(window, depth);
1905        write_pack_file();
1906        if (progress)
1907                fprintf(stderr, "Total %u (delta %u), reused %u (delta %u)\n",
1908                        written, written_delta, reused, reused_delta);
1909        return 0;
1910}