builtin/pack-objects.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "attr.h"
   5 #include "object.h"
   6 #include "blob.h"
   7 #include "commit.h"
   8 #include "tag.h"
   9 #include "tree.h"
  10 #include "delta.h"
  11 #include "pack.h"
  12 #include "pack-revindex.h"
  13 #include "csum-file.h"
  14 #include "tree-walk.h"
  15 #include "diff.h"
  16 #include "revision.h"
  17 #include "list-objects.h"
  18 #include "pack-objects.h"
  19 #include "progress.h"
  20 #include "refs.h"
  21 #include "streaming.h"
  22 #include "thread-utils.h"
  23 #include "pack-bitmap.h"
  24 #include "reachable.h"
  25 #include "sha1-array.h"
  26 #include "argv-array.h"
  27 #include "mru.h"
  28 #include "packfile.h"
  29
  30 static const char *pack_usage[] = {
  31         N_("git pack-objects --stdout [<options>...] [< <ref-list> | < <object-list>]"),
  32         N_("git pack-objects [<options>...] <base-name> [< <ref-list> | < <object-list>]"),
  33         NULL
  34 };
  35
  36 /*
  37  * Objects we are going to pack are collected in the `to_pack` structure.
  38  * It contains an array (dynamically expanded) of the object data, and a map
  39  * that can resolve SHA1s to their position in the array.
  40  */
  41 static struct packing_data to_pack;
  42
  43 static struct pack_idx_entry **written_list;
  44 static uint32_t nr_result, nr_written;
  45
  46 static int non_empty;
  47 static int reuse_delta = 1, reuse_object = 1;
  48 static int keep_unreachable, unpack_unreachable, include_tag;
  49 static timestamp_t unpack_unreachable_expiration;
  50 static int pack_loose_unreachable;
  51 static int local;
  52 static int have_non_local_packs;
  53 static int incremental;
  54 static int ignore_packed_keep;
  55 static int allow_ofs_delta;
  56 static struct pack_idx_option pack_idx_opts;
  57 static const char *base_name;
  58 static int progress = 1;
  59 static int window = 10;
  60 static unsigned long pack_size_limit;
  61 static int depth = 50;
  62 static int delta_search_threads;
  63 static int pack_to_stdout;
  64 static int num_preferred_base;
  65 static struct progress *progress_state;
  66
  67 static struct packed_git *reuse_packfile;
  68 static uint32_t reuse_packfile_objects;
  69 static off_t reuse_packfile_offset;
  70
  71 static int use_bitmap_index_default = 1;
  72 static int use_bitmap_index = -1;
  73 static int write_bitmap_index;
  74 static uint16_t write_bitmap_options;
  75
  76 static unsigned long delta_cache_size = 0;
  77 static unsigned long max_delta_cache_size = 256 * 1024 * 1024;
  78 static unsigned long cache_max_small_delta_size = 1000;
  79
  80 static unsigned long window_memory_limit = 0;
  81
  82 /*
  83  * stats
  84  */
  85 static uint32_t written, written_delta;
  86 static uint32_t reused, reused_delta;
  87
  88 /*
  89  * Indexed commits
  90  */
  91 static struct commit **indexed_commits;
  92 static unsigned int indexed_commits_nr;
  93 static unsigned int indexed_commits_alloc;
  94
  95 static void index_commit_for_bitmap(struct commit *commit)
  96 {
  97         if (indexed_commits_nr >= indexed_commits_alloc) {
  98                 indexed_commits_alloc = (indexed_commits_alloc + 32) * 2;
  99                 REALLOC_ARRAY(indexed_commits, indexed_commits_alloc);
 100         }
 101
 102         indexed_commits[indexed_commits_nr++] = commit;
 103 }
 104
 105 static void *get_delta(struct object_entry *entry)
 106 {
 107         unsigned long size, base_size, delta_size;
 108         void *buf, *base_buf, *delta_buf;
 109         enum object_type type;
 110
 111         buf = read_sha1_file(entry->idx.oid.hash, &type, &size);
 112         if (!buf)
 113                 die("unable to read %s", oid_to_hex(&entry->idx.oid));
 114         base_buf = read_sha1_file(entry->delta->idx.oid.hash, &type,
 115                                   &base_size);
 116         if (!base_buf)
 117                 die("unable to read %s",
 118                     oid_to_hex(&entry->delta->idx.oid));
 119         delta_buf = diff_delta(base_buf, base_size,
 120                                buf, size, &delta_size, 0);
 121         if (!delta_buf || delta_size != entry->delta_size)
 122                 die("delta size changed");
 123         free(buf);
 124         free(base_buf);
 125         return delta_buf;
 126 }
 127
 128 static unsigned long do_compress(void **pptr, unsigned long size)
 129 {
 130         git_zstream stream;
 131         void *in, *out;
 132         unsigned long maxsize;
 133
 134         git_deflate_init(&stream, pack_compression_level);
 135         maxsize = git_deflate_bound(&stream, size);
 136
 137         in = *pptr;
 138         out = xmalloc(maxsize);
 139         *pptr = out;
 140
 141         stream.next_in = in;
 142         stream.avail_in = size;
 143         stream.next_out = out;
 144         stream.avail_out = maxsize;
 145         while (git_deflate(&stream, Z_FINISH) == Z_OK)
 146                 ; /* nothing */
 147         git_deflate_end(&stream);
 148
 149         free(in);
 150         return stream.total_out;
 151 }
 152
 153 static unsigned long write_large_blob_data(struct git_istream *st, struct sha1file *f,
 154                                            const unsigned char *sha1)
 155 {
 156         git_zstream stream;
 157         unsigned char ibuf[1024 * 16];
 158         unsigned char obuf[1024 * 16];
 159         unsigned long olen = 0;
 160
 161         git_deflate_init(&stream, pack_compression_level);
 162
 163         for (;;) {
 164                 ssize_t readlen;
 165                 int zret = Z_OK;
 166                 readlen = read_istream(st, ibuf, sizeof(ibuf));
 167                 if (readlen == -1)
 168                         die(_("unable to read %s"), sha1_to_hex(sha1));
 169
 170                 stream.next_in = ibuf;
 171                 stream.avail_in = readlen;
 172                 while ((stream.avail_in || readlen == 0) &&
 173                        (zret == Z_OK || zret == Z_BUF_ERROR)) {
 174                         stream.next_out = obuf;
 175                         stream.avail_out = sizeof(obuf);
 176                         zret = git_deflate(&stream, readlen ? 0 : Z_FINISH);
 177                         sha1write(f, obuf, stream.next_out - obuf);
 178                         olen += stream.next_out - obuf;
 179                 }
 180                 if (stream.avail_in)
 181                         die(_("deflate error (%d)"), zret);
 182                 if (readlen == 0) {
 183                         if (zret != Z_STREAM_END)
 184                                 die(_("deflate error (%d)"), zret);
 185                         break;
 186                 }
 187         }
 188         git_deflate_end(&stream);
 189         return olen;
 190 }
 191
 192 /*
 193  * we are going to reuse the existing object data as is.  make
 194  * sure it is not corrupt.
 195  */
 196 static int check_pack_inflate(struct packed_git *p,
 197                 struct pack_window **w_curs,
 198                 off_t offset,
 199                 off_t len,
 200                 unsigned long expect)
 201 {
 202         git_zstream stream;
 203         unsigned char fakebuf[4096], *in;
 204         int st;
 205
 206         memset(&stream, 0, sizeof(stream));
 207         git_inflate_init(&stream);
 208         do {
 209                 in = use_pack(p, w_curs, offset, &stream.avail_in);
 210                 stream.next_in = in;
 211                 stream.next_out = fakebuf;
 212                 stream.avail_out = sizeof(fakebuf);
 213                 st = git_inflate(&stream, Z_FINISH);
 214                 offset += stream.next_in - in;
 215         } while (st == Z_OK || st == Z_BUF_ERROR);
 216         git_inflate_end(&stream);
 217         return (st == Z_STREAM_END &&
 218                 stream.total_out == expect &&
 219                 stream.total_in == len) ? 0 : -1;
 220 }
 221
 222 static void copy_pack_data(struct sha1file *f,
 223                 struct packed_git *p,
 224                 struct pack_window **w_curs,
 225                 off_t offset,
 226                 off_t len)
 227 {
 228         unsigned char *in;
 229         unsigned long avail;
 230
 231         while (len) {
 232                 in = use_pack(p, w_curs, offset, &avail);
 233                 if (avail > len)
 234                         avail = (unsigned long)len;
 235                 sha1write(f, in, avail);
 236                 offset += avail;
 237                 len -= avail;
 238         }
 239 }
 240
 241 /* Return 0 if we will bust the pack-size limit */
 242 static unsigned long write_no_reuse_object(struct sha1file *f, struct object_entry *entry,
 243                                            unsigned long limit, int usable_delta)
 244 {
 245         unsigned long size, datalen;
 246         unsigned char header[MAX_PACK_OBJECT_HEADER],
 247                       dheader[MAX_PACK_OBJECT_HEADER];
 248         unsigned hdrlen;
 249         enum object_type type;
 250         void *buf;
 251         struct git_istream *st = NULL;
 252
 253         if (!usable_delta) {
 254                 if (entry->type == OBJ_BLOB &&
 255                     entry->size > big_file_threshold &&
 256                     (st = open_istream(entry->idx.oid.hash, &type, &size, NULL)) != NULL)
 257                         buf = NULL;
 258                 else {
 259                         buf = read_sha1_file(entry->idx.oid.hash, &type,
 260                                              &size);
 261                         if (!buf)
 262                                 die(_("unable to read %s"),
 263                                     oid_to_hex(&entry->idx.oid));
 264                 }
 265                 /*
 266                  * make sure no cached delta data remains from a
 267                  * previous attempt before a pack split occurred.
 268                  */
 269                 FREE_AND_NULL(entry->delta_data);
 270                 entry->z_delta_size = 0;
 271         } else if (entry->delta_data) {
 272                 size = entry->delta_size;
 273                 buf = entry->delta_data;
 274                 entry->delta_data = NULL;
 275                 type = (allow_ofs_delta && entry->delta->idx.offset) ?
 276                         OBJ_OFS_DELTA : OBJ_REF_DELTA;
 277         } else {
 278                 buf = get_delta(entry);
 279                 size = entry->delta_size;
 280                 type = (allow_ofs_delta && entry->delta->idx.offset) ?
 281                         OBJ_OFS_DELTA : OBJ_REF_DELTA;
 282         }
 283
 284         if (st) /* large blob case, just assume we don't compress well */
 285                 datalen = size;
 286         else if (entry->z_delta_size)
 287                 datalen = entry->z_delta_size;
 288         else
 289                 datalen = do_compress(&buf, size);
 290
 291         /*
 292          * The object header is a byte of 'type' followed by zero or
 293          * more bytes of length.
 294          */
 295         hdrlen = encode_in_pack_object_header(header, sizeof(header),
 296                                               type, size);
 297
 298         if (type == OBJ_OFS_DELTA) {
 299                 /*
 300                  * Deltas with relative base contain an additional
 301                  * encoding of the relative offset for the delta
 302                  * base from this object's position in the pack.
 303                  */
 304                 off_t ofs = entry->idx.offset - entry->delta->idx.offset;
 305                 unsigned pos = sizeof(dheader) - 1;
 306                 dheader[pos] = ofs & 127;
 307                 while (ofs >>= 7)
 308                         dheader[--pos] = 128 | (--ofs & 127);
 309                 if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
 310                         if (st)
 311                                 close_istream(st);
 312                         free(buf);
 313                         return 0;
 314                 }
 315                 sha1write(f, header, hdrlen);
 316                 sha1write(f, dheader + pos, sizeof(dheader) - pos);
 317                 hdrlen += sizeof(dheader) - pos;
 318         } else if (type == OBJ_REF_DELTA) {
 319                 /*
 320                  * Deltas with a base reference contain
 321                  * an additional 20 bytes for the base sha1.
 322                  */
 323                 if (limit && hdrlen + 20 + datalen + 20 >= limit) {
 324                         if (st)
 325                                 close_istream(st);
 326                         free(buf);
 327                         return 0;
 328                 }
 329                 sha1write(f, header, hdrlen);
 330                 sha1write(f, entry->delta->idx.oid.hash, 20);
 331                 hdrlen += 20;
 332         } else {
 333                 if (limit && hdrlen + datalen + 20 >= limit) {
 334                         if (st)
 335                                 close_istream(st);
 336                         free(buf);
 337                         return 0;
 338                 }
 339                 sha1write(f, header, hdrlen);
 340         }
 341         if (st) {
 342                 datalen = write_large_blob_data(st, f, entry->idx.oid.hash);
 343                 close_istream(st);
 344         } else {
 345                 sha1write(f, buf, datalen);
 346                 free(buf);
 347         }
 348
 349         return hdrlen + datalen;
 350 }
 351
 352 /* Return 0 if we will bust the pack-size limit */
 353 static off_t write_reuse_object(struct sha1file *f, struct object_entry *entry,
 354                                 unsigned long limit, int usable_delta)
 355 {
 356         struct packed_git *p = entry->in_pack;
 357         struct pack_window *w_curs = NULL;
 358         struct revindex_entry *revidx;
 359         off_t offset;
 360         enum object_type type = entry->type;
 361         off_t datalen;
 362         unsigned char header[MAX_PACK_OBJECT_HEADER],
 363                       dheader[MAX_PACK_OBJECT_HEADER];
 364         unsigned hdrlen;
 365
 366         if (entry->delta)
 367                 type = (allow_ofs_delta && entry->delta->idx.offset) ?
 368                         OBJ_OFS_DELTA : OBJ_REF_DELTA;
 369         hdrlen = encode_in_pack_object_header(header, sizeof(header),
 370                                               type, entry->size);
 371
 372         offset = entry->in_pack_offset;
 373         revidx = find_pack_revindex(p, offset);
 374         datalen = revidx[1].offset - offset;
 375         if (!pack_to_stdout && p->index_version > 1 &&
 376             check_pack_crc(p, &w_curs, offset, datalen, revidx->nr)) {
 377                 error("bad packed object CRC for %s",
 378                       oid_to_hex(&entry->idx.oid));
 379                 unuse_pack(&w_curs);
 380                 return write_no_reuse_object(f, entry, limit, usable_delta);
 381         }
 382
 383         offset += entry->in_pack_header_size;
 384         datalen -= entry->in_pack_header_size;
 385
 386         if (!pack_to_stdout && p->index_version == 1 &&
 387             check_pack_inflate(p, &w_curs, offset, datalen, entry->size)) {
 388                 error("corrupt packed object for %s",
 389                       oid_to_hex(&entry->idx.oid));
 390                 unuse_pack(&w_curs);
 391                 return write_no_reuse_object(f, entry, limit, usable_delta);
 392         }
 393
 394         if (type == OBJ_OFS_DELTA) {
 395                 off_t ofs = entry->idx.offset - entry->delta->idx.offset;
 396                 unsigned pos = sizeof(dheader) - 1;
 397                 dheader[pos] = ofs & 127;
 398                 while (ofs >>= 7)
 399                         dheader[--pos] = 128 | (--ofs & 127);
 400                 if (limit && hdrlen + sizeof(dheader) - pos + datalen + 20 >= limit) {
 401                         unuse_pack(&w_curs);
 402                         return 0;
 403                 }
 404                 sha1write(f, header, hdrlen);
 405                 sha1write(f, dheader + pos, sizeof(dheader) - pos);
 406                 hdrlen += sizeof(dheader) - pos;
 407                 reused_delta++;
 408         } else if (type == OBJ_REF_DELTA) {
 409                 if (limit && hdrlen + 20 + datalen + 20 >= limit) {
 410                         unuse_pack(&w_curs);
 411                         return 0;
 412                 }
 413                 sha1write(f, header, hdrlen);
 414                 sha1write(f, entry->delta->idx.oid.hash, 20);
 415                 hdrlen += 20;
 416                 reused_delta++;
 417         } else {
 418                 if (limit && hdrlen + datalen + 20 >= limit) {
 419                         unuse_pack(&w_curs);
 420                         return 0;
 421                 }
 422                 sha1write(f, header, hdrlen);
 423         }
 424         copy_pack_data(f, p, &w_curs, offset, datalen);
 425         unuse_pack(&w_curs);
 426         reused++;
 427         return hdrlen + datalen;
 428 }
 429
 430 /* Return 0 if we will bust the pack-size limit */
 431 static off_t write_object(struct sha1file *f,
 432                           struct object_entry *entry,
 433                           off_t write_offset)
 434 {
 435         unsigned long limit;
 436         off_t len;
 437         int usable_delta, to_reuse;
 438
 439         if (!pack_to_stdout)
 440                 crc32_begin(f);
 441
 442         /* apply size limit if limited packsize and not first object */
 443         if (!pack_size_limit || !nr_written)
 444                 limit = 0;
 445         else if (pack_size_limit <= write_offset)
 446                 /*
 447                  * the earlier object did not fit the limit; avoid
 448                  * mistaking this with unlimited (i.e. limit = 0).
 449                  */
 450                 limit = 1;
 451         else
 452                 limit = pack_size_limit - write_offset;
 453
 454         if (!entry->delta)
 455                 usable_delta = 0;       /* no delta */
 456         else if (!pack_size_limit)
 457                usable_delta = 1;        /* unlimited packfile */
 458         else if (entry->delta->idx.offset == (off_t)-1)
 459                 usable_delta = 0;       /* base was written to another pack */
 460         else if (entry->delta->idx.offset)
 461                 usable_delta = 1;       /* base already exists in this pack */
 462         else
 463                 usable_delta = 0;       /* base could end up in another pack */
 464
 465         if (!reuse_object)
 466                 to_reuse = 0;   /* explicit */
 467         else if (!entry->in_pack)
 468                 to_reuse = 0;   /* can't reuse what we don't have */
 469         else if (entry->type == OBJ_REF_DELTA || entry->type == OBJ_OFS_DELTA)
 470                                 /* check_object() decided it for us ... */
 471                 to_reuse = usable_delta;
 472                                 /* ... but pack split may override that */
 473         else if (entry->type != entry->in_pack_type)
 474                 to_reuse = 0;   /* pack has delta which is unusable */
 475         else if (entry->delta)
 476                 to_reuse = 0;   /* we want to pack afresh */
 477         else
 478                 to_reuse = 1;   /* we have it in-pack undeltified,
 479                                  * and we do not need to deltify it.
 480                                  */
 481
 482         if (!to_reuse)
 483                 len = write_no_reuse_object(f, entry, limit, usable_delta);
 484         else
 485                 len = write_reuse_object(f, entry, limit, usable_delta);
 486         if (!len)
 487                 return 0;
 488
 489         if (usable_delta)
 490                 written_delta++;
 491         written++;
 492         if (!pack_to_stdout)
 493                 entry->idx.crc32 = crc32_end(f);
 494         return len;
 495 }
 496
 497 enum write_one_status {
 498         WRITE_ONE_SKIP = -1, /* already written */
 499         WRITE_ONE_BREAK = 0, /* writing this will bust the limit; not written */
 500         WRITE_ONE_WRITTEN = 1, /* normal */
 501         WRITE_ONE_RECURSIVE = 2 /* already scheduled to be written */
 502 };
 503
 504 static enum write_one_status write_one(struct sha1file *f,
 505                                        struct object_entry *e,
 506                                        off_t *offset)
 507 {
 508         off_t size;
 509         int recursing;
 510
 511         /*
 512          * we set offset to 1 (which is an impossible value) to mark
 513          * the fact that this object is involved in "write its base
 514          * first before writing a deltified object" recursion.
 515          */
 516         recursing = (e->idx.offset == 1);
 517         if (recursing) {
 518                 warning("recursive delta detected for object %s",
 519                         oid_to_hex(&e->idx.oid));
 520                 return WRITE_ONE_RECURSIVE;
 521         } else if (e->idx.offset || e->preferred_base) {
 522                 /* offset is non zero if object is written already. */
 523                 return WRITE_ONE_SKIP;
 524         }
 525
 526         /* if we are deltified, write out base object first. */
 527         if (e->delta) {
 528                 e->idx.offset = 1; /* now recurse */
 529                 switch (write_one(f, e->delta, offset)) {
 530                 case WRITE_ONE_RECURSIVE:
 531                         /* we cannot depend on this one */
 532                         e->delta = NULL;
 533                         break;
 534                 default:
 535                         break;
 536                 case WRITE_ONE_BREAK:
 537                         e->idx.offset = recursing;
 538                         return WRITE_ONE_BREAK;
 539                 }
 540         }
 541
 542         e->idx.offset = *offset;
 543         size = write_object(f, e, *offset);
 544         if (!size) {
 545                 e->idx.offset = recursing;
 546                 return WRITE_ONE_BREAK;
 547         }
 548         written_list[nr_written++] = &e->idx;
 549
 550         /* make sure off_t is sufficiently large not to wrap */
 551         if (signed_add_overflows(*offset, size))
 552                 die("pack too large for current definition of off_t");
 553         *offset += size;
 554         return WRITE_ONE_WRITTEN;
 555 }
 556
 557 static int mark_tagged(const char *path, const struct object_id *oid, int flag,
 558                        void *cb_data)
 559 {
 560         unsigned char peeled[20];
 561         struct object_entry *entry = packlist_find(&to_pack, oid->hash, NULL);
 562
 563         if (entry)
 564                 entry->tagged = 1;
 565         if (!peel_ref(path, peeled)) {
 566                 entry = packlist_find(&to_pack, peeled, NULL);
 567                 if (entry)
 568                         entry->tagged = 1;
 569         }
 570         return 0;
 571 }
 572
 573 static inline void add_to_write_order(struct object_entry **wo,
 574                                unsigned int *endp,
 575                                struct object_entry *e)
 576 {
 577         if (e->filled)
 578                 return;
 579         wo[(*endp)++] = e;
 580         e->filled = 1;
 581 }
 582
 583 static void add_descendants_to_write_order(struct object_entry **wo,
 584                                            unsigned int *endp,
 585                                            struct object_entry *e)
 586 {
 587         int add_to_order = 1;
 588         while (e) {
 589                 if (add_to_order) {
 590                         struct object_entry *s;
 591                         /* add this node... */
 592                         add_to_write_order(wo, endp, e);
 593                         /* all its siblings... */
 594                         for (s = e->delta_sibling; s; s = s->delta_sibling) {
 595                                 add_to_write_order(wo, endp, s);
 596                         }
 597                 }
 598                 /* drop down a level to add left subtree nodes if possible */
 599                 if (e->delta_child) {
 600                         add_to_order = 1;
 601                         e = e->delta_child;
 602                 } else {
 603                         add_to_order = 0;
 604                         /* our sibling might have some children, it is next */
 605                         if (e->delta_sibling) {
 606                                 e = e->delta_sibling;
 607                                 continue;
 608                         }
 609                         /* go back to our parent node */
 610                         e = e->delta;
 611                         while (e && !e->delta_sibling) {
 612                                 /* we're on the right side of a subtree, keep
 613                                  * going up until we can go right again */
 614                                 e = e->delta;
 615                         }
 616                         if (!e) {
 617                                 /* done- we hit our original root node */
 618                                 return;
 619                         }
 620                         /* pass it off to sibling at this level */
 621                         e = e->delta_sibling;
 622                 }
 623         };
 624 }
 625
 626 static void add_family_to_write_order(struct object_entry **wo,
 627                                       unsigned int *endp,
 628                                       struct object_entry *e)
 629 {
 630         struct object_entry *root;
 631
 632         for (root = e; root->delta; root = root->delta)
 633                 ; /* nothing */
 634         add_descendants_to_write_order(wo, endp, root);
 635 }
 636
 637 static struct object_entry **compute_write_order(void)
 638 {
 639         unsigned int i, wo_end, last_untagged;
 640
 641         struct object_entry **wo;
 642         struct object_entry *objects = to_pack.objects;
 643
 644         for (i = 0; i < to_pack.nr_objects; i++) {
 645                 objects[i].tagged = 0;
 646                 objects[i].filled = 0;
 647                 objects[i].delta_child = NULL;
 648                 objects[i].delta_sibling = NULL;
 649         }
 650
 651         /*
 652          * Fully connect delta_child/delta_sibling network.
 653          * Make sure delta_sibling is sorted in the original
 654          * recency order.
 655          */
 656         for (i = to_pack.nr_objects; i > 0;) {
 657                 struct object_entry *e = &objects[--i];
 658                 if (!e->delta)
 659                         continue;
 660                 /* Mark me as the first child */
 661                 e->delta_sibling = e->delta->delta_child;
 662                 e->delta->delta_child = e;
 663         }
 664
 665         /*
 666          * Mark objects that are at the tip of tags.
 667          */
 668         for_each_tag_ref(mark_tagged, NULL);
 669
 670         /*
 671          * Give the objects in the original recency order until
 672          * we see a tagged tip.
 673          */
 674         ALLOC_ARRAY(wo, to_pack.nr_objects);
 675         for (i = wo_end = 0; i < to_pack.nr_objects; i++) {
 676                 if (objects[i].tagged)
 677                         break;
 678                 add_to_write_order(wo, &wo_end, &objects[i]);
 679         }
 680         last_untagged = i;
 681
 682         /*
 683          * Then fill all the tagged tips.
 684          */
 685         for (; i < to_pack.nr_objects; i++) {
 686                 if (objects[i].tagged)
 687                         add_to_write_order(wo, &wo_end, &objects[i]);
 688         }
 689
 690         /*
 691          * And then all remaining commits and tags.
 692          */
 693         for (i = last_untagged; i < to_pack.nr_objects; i++) {
 694                 if (objects[i].type != OBJ_COMMIT &&
 695                     objects[i].type != OBJ_TAG)
 696                         continue;
 697                 add_to_write_order(wo, &wo_end, &objects[i]);
 698         }
 699
 700         /*
 701          * And then all the trees.
 702          */
 703         for (i = last_untagged; i < to_pack.nr_objects; i++) {
 704                 if (objects[i].type != OBJ_TREE)
 705                         continue;
 706                 add_to_write_order(wo, &wo_end, &objects[i]);
 707         }
 708
 709         /*
 710          * Finally all the rest in really tight order
 711          */
 712         for (i = last_untagged; i < to_pack.nr_objects; i++) {
 713                 if (!objects[i].filled)
 714                         add_family_to_write_order(wo, &wo_end, &objects[i]);
 715         }
 716
 717         if (wo_end != to_pack.nr_objects)
 718                 die("ordered %u objects, expected %"PRIu32, wo_end, to_pack.nr_objects);
 719
 720         return wo;
 721 }
 722
 723 static off_t write_reused_pack(struct sha1file *f)
 724 {
 725         unsigned char buffer[8192];
 726         off_t to_write, total;
 727         int fd;
 728
 729         if (!is_pack_valid(reuse_packfile))
 730                 die("packfile is invalid: %s", reuse_packfile->pack_name);
 731
 732         fd = git_open(reuse_packfile->pack_name);
 733         if (fd < 0)
 734                 die_errno("unable to open packfile for reuse: %s",
 735                           reuse_packfile->pack_name);
 736
 737         if (lseek(fd, sizeof(struct pack_header), SEEK_SET) == -1)
 738                 die_errno("unable to seek in reused packfile");
 739
 740         if (reuse_packfile_offset < 0)
 741                 reuse_packfile_offset = reuse_packfile->pack_size - 20;
 742
 743         total = to_write = reuse_packfile_offset - sizeof(struct pack_header);
 744
 745         while (to_write) {
 746                 int read_pack = xread(fd, buffer, sizeof(buffer));
 747
 748                 if (read_pack <= 0)
 749                         die_errno("unable to read from reused packfile");
 750
 751                 if (read_pack > to_write)
 752                         read_pack = to_write;
 753
 754                 sha1write(f, buffer, read_pack);
 755                 to_write -= read_pack;
 756
 757                 /*
 758                  * We don't know the actual number of objects written,
 759                  * only how many bytes written, how many bytes total, and
 760                  * how many objects total. So we can fake it by pretending all
 761                  * objects we are writing are the same size. This gives us a
 762                  * smooth progress meter, and at the end it matches the true
 763                  * answer.
 764                  */
 765                 written = reuse_packfile_objects *
 766                                 (((double)(total - to_write)) / total);
 767                 display_progress(progress_state, written);
 768         }
 769
 770         close(fd);
 771         written = reuse_packfile_objects;
 772         display_progress(progress_state, written);
 773         return reuse_packfile_offset - sizeof(struct pack_header);
 774 }
 775
 776 static const char no_split_warning[] = N_(
 777 "disabling bitmap writing, packs are split due to pack.packSizeLimit"
 778 );
 779
 780 static void write_pack_file(void)
 781 {
 782         uint32_t i = 0, j;
 783         struct sha1file *f;
 784         off_t offset;
 785         uint32_t nr_remaining = nr_result;
 786         time_t last_mtime = 0;
 787         struct object_entry **write_order;
 788
 789         if (progress > pack_to_stdout)
 790                 progress_state = start_progress(_("Writing objects"), nr_result);
 791         ALLOC_ARRAY(written_list, to_pack.nr_objects);
 792         write_order = compute_write_order();
 793
 794         do {
 795                 unsigned char sha1[20];
 796                 char *pack_tmp_name = NULL;
 797
 798                 if (pack_to_stdout)
 799                         f = sha1fd_throughput(1, "<stdout>", progress_state);
 800                 else
 801                         f = create_tmp_packfile(&pack_tmp_name);
 802
 803                 offset = write_pack_header(f, nr_remaining);
 804
 805                 if (reuse_packfile) {
 806                         off_t packfile_size;
 807                         assert(pack_to_stdout);
 808
 809                         packfile_size = write_reused_pack(f);
 810                         offset += packfile_size;
 811                 }
 812
 813                 nr_written = 0;
 814                 for (; i < to_pack.nr_objects; i++) {
 815                         struct object_entry *e = write_order[i];
 816                         if (write_one(f, e, &offset) == WRITE_ONE_BREAK)
 817                                 break;
 818                         display_progress(progress_state, written);
 819                 }
 820
 821                 /*
 822                  * Did we write the wrong # entries in the header?
 823                  * If so, rewrite it like in fast-import
 824                  */
 825                 if (pack_to_stdout) {
 826                         sha1close(f, sha1, CSUM_CLOSE);
 827                 } else if (nr_written == nr_remaining) {
 828                         sha1close(f, sha1, CSUM_FSYNC);
 829                 } else {
 830                         int fd = sha1close(f, sha1, 0);
 831                         fixup_pack_header_footer(fd, sha1, pack_tmp_name,
 832                                                  nr_written, sha1, offset);
 833                         close(fd);
 834                         if (write_bitmap_index) {
 835                                 warning(_(no_split_warning));
 836                                 write_bitmap_index = 0;
 837                         }
 838                 }
 839
 840                 if (!pack_to_stdout) {
 841                         struct stat st;
 842                         struct strbuf tmpname = STRBUF_INIT;
 843
 844                         /*
 845                          * Packs are runtime accessed in their mtime
 846                          * order since newer packs are more likely to contain
 847                          * younger objects.  So if we are creating multiple
 848                          * packs then we should modify the mtime of later ones
 849                          * to preserve this property.
 850                          */
 851                         if (stat(pack_tmp_name, &st) < 0) {
 852                                 warning_errno("failed to stat %s", pack_tmp_name);
 853                         } else if (!last_mtime) {
 854                                 last_mtime = st.st_mtime;
 855                         } else {
 856                                 struct utimbuf utb;
 857                                 utb.actime = st.st_atime;
 858                                 utb.modtime = --last_mtime;
 859                                 if (utime(pack_tmp_name, &utb) < 0)
 860                                         warning_errno("failed utime() on %s", pack_tmp_name);
 861                         }
 862
 863                         strbuf_addf(&tmpname, "%s-", base_name);
 864
 865                         if (write_bitmap_index) {
 866                                 bitmap_writer_set_checksum(sha1);
 867                                 bitmap_writer_build_type_index(written_list, nr_written);
 868                         }
 869
 870                         finish_tmp_packfile(&tmpname, pack_tmp_name,
 871                                             written_list, nr_written,
 872                                             &pack_idx_opts, sha1);
 873
 874                         if (write_bitmap_index) {
 875                                 strbuf_addf(&tmpname, "%s.bitmap", sha1_to_hex(sha1));
 876
 877                                 stop_progress(&progress_state);
 878
 879                                 bitmap_writer_show_progress(progress);
 880                                 bitmap_writer_reuse_bitmaps(&to_pack);
 881                                 bitmap_writer_select_commits(indexed_commits, indexed_commits_nr, -1);
 882                                 bitmap_writer_build(&to_pack);
 883                                 bitmap_writer_finish(written_list, nr_written,
 884                                                      tmpname.buf, write_bitmap_options);
 885                                 write_bitmap_index = 0;
 886                         }
 887
 888                         strbuf_release(&tmpname);
 889                         free(pack_tmp_name);
 890                         puts(sha1_to_hex(sha1));
 891                 }
 892
 893                 /* mark written objects as written to previous pack */
 894                 for (j = 0; j < nr_written; j++) {
 895                         written_list[j]->offset = (off_t)-1;
 896                 }
 897                 nr_remaining -= nr_written;
 898         } while (nr_remaining && i < to_pack.nr_objects);
 899
 900         free(written_list);
 901         free(write_order);
 902         stop_progress(&progress_state);
 903         if (written != nr_result)
 904                 die("wrote %"PRIu32" objects while expecting %"PRIu32,
 905                         written, nr_result);
 906 }
 907
 908 static int no_try_delta(const char *path)
 909 {
 910         static struct attr_check *check;
 911
 912         if (!check)
 913                 check = attr_check_initl("delta", NULL);
 914         if (git_check_attr(path, check))
 915                 return 0;
 916         if (ATTR_FALSE(check->items[0].value))
 917                 return 1;
 918         return 0;
 919 }
 920
 921 /*
 922  * When adding an object, check whether we have already added it
 923  * to our packing list. If so, we can skip. However, if we are
 924  * being asked to excludei t, but the previous mention was to include
 925  * it, make sure to adjust its flags and tweak our numbers accordingly.
 926  *
 927  * As an optimization, we pass out the index position where we would have
 928  * found the item, since that saves us from having to look it up again a
 929  * few lines later when we want to add the new entry.
 930  */
 931 static int have_duplicate_entry(const unsigned char *sha1,
 932                                 int exclude,
 933                                 uint32_t *index_pos)
 934 {
 935         struct object_entry *entry;
 936
 937         entry = packlist_find(&to_pack, sha1, index_pos);
 938         if (!entry)
 939                 return 0;
 940
 941         if (exclude) {
 942                 if (!entry->preferred_base)
 943                         nr_result--;
 944                 entry->preferred_base = 1;
 945         }
 946
 947         return 1;
 948 }
 949
 950 static int want_found_object(int exclude, struct packed_git *p)
 951 {
 952         if (exclude)
 953                 return 1;
 954         if (incremental)
 955                 return 0;
 956
 957         /*
 958          * When asked to do --local (do not include an object that appears in a
 959          * pack we borrow from elsewhere) or --honor-pack-keep (do not include
 960          * an object that appears in a pack marked with .keep), finding a pack
 961          * that matches the criteria is sufficient for us to decide to omit it.
 962          * However, even if this pack does not satisfy the criteria, we need to
 963          * make sure no copy of this object appears in _any_ pack that makes us
 964          * to omit the object, so we need to check all the packs.
 965          *
 966          * We can however first check whether these options can possible matter;
 967          * if they do not matter we know we want the object in generated pack.
 968          * Otherwise, we signal "-1" at the end to tell the caller that we do
 969          * not know either way, and it needs to check more packs.
 970          */
 971         if (!ignore_packed_keep &&
 972             (!local || !have_non_local_packs))
 973                 return 1;
 974
 975         if (local && !p->pack_local)
 976                 return 0;
 977         if (ignore_packed_keep && p->pack_local && p->pack_keep)
 978                 return 0;
 979
 980         /* we don't know yet; keep looking for more packs */
 981         return -1;
 982 }
 983
 984 /*
 985  * Check whether we want the object in the pack (e.g., we do not want
 986  * objects found in non-local stores if the "--local" option was used).
 987  *
 988  * If the caller already knows an existing pack it wants to take the object
 989  * from, that is passed in *found_pack and *found_offset; otherwise this
 990  * function finds if there is any pack that has the object and returns the pack
 991  * and its offset in these variables.
 992  */
 993 static int want_object_in_pack(const unsigned char *sha1,
 994                                int exclude,
 995                                struct packed_git **found_pack,
 996                                off_t *found_offset)
 997 {
 998         struct mru_entry *entry;
 999         int want;
1000
1001         if (!exclude && local && has_loose_object_nonlocal(sha1))
1002                 return 0;
1003
1004         /*
1005          * If we already know the pack object lives in, start checks from that
1006          * pack - in the usual case when neither --local was given nor .keep files
1007          * are present we will determine the answer right now.
1008          */
1009         if (*found_pack) {
1010                 want = want_found_object(exclude, *found_pack);
1011                 if (want != -1)
1012                         return want;
1013         }
1014
1015         for (entry = packed_git_mru.head; entry; entry = entry->next) {
1016                 struct packed_git *p = entry->item;
1017                 off_t offset;
1018
1019                 if (p == *found_pack)
1020                         offset = *found_offset;
1021                 else
1022                         offset = find_pack_entry_one(sha1, p);
1023
1024                 if (offset) {
1025                         if (!*found_pack) {
1026                                 if (!is_pack_valid(p))
1027                                         continue;
1028                                 *found_offset = offset;
1029                                 *found_pack = p;
1030                         }
1031                         want = want_found_object(exclude, p);
1032                         if (!exclude && want > 0)
1033                                 mru_mark(&packed_git_mru, entry);
1034                         if (want != -1)
1035                                 return want;
1036                 }
1037         }
1038
1039         return 1;
1040 }
1041
1042 static void create_object_entry(const unsigned char *sha1,
1043                                 enum object_type type,
1044                                 uint32_t hash,
1045                                 int exclude,
1046                                 int no_try_delta,
1047                                 uint32_t index_pos,
1048                                 struct packed_git *found_pack,
1049                                 off_t found_offset)
1050 {
1051         struct object_entry *entry;
1052
1053         entry = packlist_alloc(&to_pack, sha1, index_pos);
1054         entry->hash = hash;
1055         if (type)
1056                 entry->type = type;
1057         if (exclude)
1058                 entry->preferred_base = 1;
1059         else
1060                 nr_result++;
1061         if (found_pack) {
1062                 entry->in_pack = found_pack;
1063                 entry->in_pack_offset = found_offset;
1064         }
1065
1066         entry->no_try_delta = no_try_delta;
1067 }
1068
1069 static const char no_closure_warning[] = N_(
1070 "disabling bitmap writing, as some objects are not being packed"
1071 );
1072
1073 static int add_object_entry(const unsigned char *sha1, enum object_type type,
1074                             const char *name, int exclude)
1075 {
1076         struct packed_git *found_pack = NULL;
1077         off_t found_offset = 0;
1078         uint32_t index_pos;
1079
1080         if (have_duplicate_entry(sha1, exclude, &index_pos))
1081                 return 0;
1082
1083         if (!want_object_in_pack(sha1, exclude, &found_pack, &found_offset)) {
1084                 /* The pack is missing an object, so it will not have closure */
1085                 if (write_bitmap_index) {
1086                         warning(_(no_closure_warning));
1087                         write_bitmap_index = 0;
1088                 }
1089                 return 0;
1090         }
1091
1092         create_object_entry(sha1, type, pack_name_hash(name),
1093                             exclude, name && no_try_delta(name),
1094                             index_pos, found_pack, found_offset);
1095
1096         display_progress(progress_state, nr_result);
1097         return 1;
1098 }
1099
1100 static int add_object_entry_from_bitmap(const unsigned char *sha1,
1101                                         enum object_type type,
1102                                         int flags, uint32_t name_hash,
1103                                         struct packed_git *pack, off_t offset)
1104 {
1105         uint32_t index_pos;
1106
1107         if (have_duplicate_entry(sha1, 0, &index_pos))
1108                 return 0;
1109
1110         if (!want_object_in_pack(sha1, 0, &pack, &offset))
1111                 return 0;
1112
1113         create_object_entry(sha1, type, name_hash, 0, 0, index_pos, pack, offset);
1114
1115         display_progress(progress_state, nr_result);
1116         return 1;
1117 }
1118
1119 struct pbase_tree_cache {
1120         unsigned char sha1[20];
1121         int ref;
1122         int temporary;
1123         void *tree_data;
1124         unsigned long tree_size;
1125 };
1126
1127 static struct pbase_tree_cache *(pbase_tree_cache[256]);
1128 static int pbase_tree_cache_ix(const unsigned char *sha1)
1129 {
1130         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
1131 }
1132 static int pbase_tree_cache_ix_incr(int ix)
1133 {
1134         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
1135 }
1136
1137 static struct pbase_tree {
1138         struct pbase_tree *next;
1139         /* This is a phony "cache" entry; we are not
1140          * going to evict it or find it through _get()
1141          * mechanism -- this is for the toplevel node that
1142          * would almost always change with any commit.
1143          */
1144         struct pbase_tree_cache pcache;
1145 } *pbase_tree;
1146
1147 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
1148 {
1149         struct pbase_tree_cache *ent, *nent;
1150         void *data;
1151         unsigned long size;
1152         enum object_type type;
1153         int neigh;
1154         int my_ix = pbase_tree_cache_ix(sha1);
1155         int available_ix = -1;
1156
1157         /* pbase-tree-cache acts as a limited hashtable.
1158          * your object will be found at your index or within a few
1159          * slots after that slot if it is cached.
1160          */
1161         for (neigh = 0; neigh < 8; neigh++) {
1162                 ent = pbase_tree_cache[my_ix];
1163                 if (ent && !hashcmp(ent->sha1, sha1)) {
1164                         ent->ref++;
1165                         return ent;
1166                 }
1167                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
1168                          ((0 <= available_ix) &&
1169                           (!ent && pbase_tree_cache[available_ix])))
1170                         available_ix = my_ix;
1171                 if (!ent)
1172                         break;
1173                 my_ix = pbase_tree_cache_ix_incr(my_ix);
1174         }
1175
1176         /* Did not find one.  Either we got a bogus request or
1177          * we need to read and perhaps cache.
1178          */
1179         data = read_sha1_file(sha1, &type, &size);
1180         if (!data)
1181                 return NULL;
1182         if (type != OBJ_TREE) {
1183                 free(data);
1184                 return NULL;
1185         }
1186
1187         /* We need to either cache or return a throwaway copy */
1188
1189         if (available_ix < 0)
1190                 ent = NULL;
1191         else {
1192                 ent = pbase_tree_cache[available_ix];
1193                 my_ix = available_ix;
1194         }
1195
1196         if (!ent) {
1197                 nent = xmalloc(sizeof(*nent));
1198                 nent->temporary = (available_ix < 0);
1199         }
1200         else {
1201                 /* evict and reuse */
1202                 free(ent->tree_data);
1203                 nent = ent;
1204         }
1205         hashcpy(nent->sha1, sha1);
1206         nent->tree_data = data;
1207         nent->tree_size = size;
1208         nent->ref = 1;
1209         if (!nent->temporary)
1210                 pbase_tree_cache[my_ix] = nent;
1211         return nent;
1212 }
1213
1214 static void pbase_tree_put(struct pbase_tree_cache *cache)
1215 {
1216         if (!cache->temporary) {
1217                 cache->ref--;
1218                 return;
1219         }
1220         free(cache->tree_data);
1221         free(cache);
1222 }
1223
1224 static int name_cmp_len(const char *name)
1225 {
1226         int i;
1227         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
1228                 ;
1229         return i;
1230 }
1231
1232 static void add_pbase_object(struct tree_desc *tree,
1233                              const char *name,
1234                              int cmplen,
1235                              const char *fullname)
1236 {
1237         struct name_entry entry;
1238         int cmp;
1239
1240         while (tree_entry(tree,&entry)) {
1241                 if (S_ISGITLINK(entry.mode))
1242                         continue;
1243                 cmp = tree_entry_len(&entry) != cmplen ? 1 :
1244                       memcmp(name, entry.path, cmplen);
1245                 if (cmp > 0)
1246                         continue;
1247                 if (cmp < 0)
1248                         return;
1249                 if (name[cmplen] != '/') {
1250                         add_object_entry(entry.oid->hash,
1251                                          object_type(entry.mode),
1252                                          fullname, 1);
1253                         return;
1254                 }
1255                 if (S_ISDIR(entry.mode)) {
1256                         struct tree_desc sub;
1257                         struct pbase_tree_cache *tree;
1258                         const char *down = name+cmplen+1;
1259                         int downlen = name_cmp_len(down);
1260
1261                         tree = pbase_tree_get(entry.oid->hash);
1262                         if (!tree)
1263                                 return;
1264                         init_tree_desc(&sub, tree->tree_data, tree->tree_size);
1265
1266                         add_pbase_object(&sub, down, downlen, fullname);
1267                         pbase_tree_put(tree);
1268                 }
1269         }
1270 }
1271
1272 static unsigned *done_pbase_paths;
1273 static int done_pbase_paths_num;
1274 static int done_pbase_paths_alloc;
1275 static int done_pbase_path_pos(unsigned hash)
1276 {
1277         int lo = 0;
1278         int hi = done_pbase_paths_num;
1279         while (lo < hi) {
1280                 int mi = lo + (hi - lo) / 2;
1281                 if (done_pbase_paths[mi] == hash)
1282                         return mi;
1283                 if (done_pbase_paths[mi] < hash)
1284                         hi = mi;
1285                 else
1286                         lo = mi + 1;
1287         }
1288         return -lo-1;
1289 }
1290
1291 static int check_pbase_path(unsigned hash)
1292 {
1293         int pos = done_pbase_path_pos(hash);
1294         if (0 <= pos)
1295                 return 1;
1296         pos = -pos - 1;
1297         ALLOC_GROW(done_pbase_paths,
1298                    done_pbase_paths_num + 1,
1299                    done_pbase_paths_alloc);
1300         done_pbase_paths_num++;
1301         if (pos < done_pbase_paths_num)
1302                 MOVE_ARRAY(done_pbase_paths + pos + 1, done_pbase_paths + pos,
1303                            done_pbase_paths_num - pos - 1);
1304         done_pbase_paths[pos] = hash;
1305         return 0;
1306 }
1307
1308 static void add_preferred_base_object(const char *name)
1309 {
1310         struct pbase_tree *it;
1311         int cmplen;
1312         unsigned hash = pack_name_hash(name);
1313
1314         if (!num_preferred_base || check_pbase_path(hash))
1315                 return;
1316
1317         cmplen = name_cmp_len(name);
1318         for (it = pbase_tree; it; it = it->next) {
1319                 if (cmplen == 0) {
1320                         add_object_entry(it->pcache.sha1, OBJ_TREE, NULL, 1);
1321                 }
1322                 else {
1323                         struct tree_desc tree;
1324                         init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
1325                         add_pbase_object(&tree, name, cmplen, name);
1326                 }
1327         }
1328 }
1329
1330 static void add_preferred_base(unsigned char *sha1)
1331 {
1332         struct pbase_tree *it;
1333         void *data;
1334         unsigned long size;
1335         unsigned char tree_sha1[20];
1336
1337         if (window <= num_preferred_base++)
1338                 return;
1339
1340         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
1341         if (!data)
1342                 return;
1343
1344         for (it = pbase_tree; it; it = it->next) {
1345                 if (!hashcmp(it->pcache.sha1, tree_sha1)) {
1346                         free(data);
1347                         return;
1348                 }
1349         }
1350
1351         it = xcalloc(1, sizeof(*it));
1352         it->next = pbase_tree;
1353         pbase_tree = it;
1354
1355         hashcpy(it->pcache.sha1, tree_sha1);
1356         it->pcache.tree_data = data;
1357         it->pcache.tree_size = size;
1358 }
1359
1360 static void cleanup_preferred_base(void)
1361 {
1362         struct pbase_tree *it;
1363         unsigned i;
1364
1365         it = pbase_tree;
1366         pbase_tree = NULL;
1367         while (it) {
1368                 struct pbase_tree *this = it;
1369                 it = this->next;
1370                 free(this->pcache.tree_data);
1371                 free(this);
1372         }
1373
1374         for (i = 0; i < ARRAY_SIZE(pbase_tree_cache); i++) {
1375                 if (!pbase_tree_cache[i])
1376                         continue;
1377                 free(pbase_tree_cache[i]->tree_data);
1378                 FREE_AND_NULL(pbase_tree_cache[i]);
1379         }
1380
1381         FREE_AND_NULL(done_pbase_paths);
1382         done_pbase_paths_num = done_pbase_paths_alloc = 0;
1383 }
1384
1385 static void check_object(struct object_entry *entry)
1386 {
1387         if (entry->in_pack) {
1388                 struct packed_git *p = entry->in_pack;
1389                 struct pack_window *w_curs = NULL;
1390                 const unsigned char *base_ref = NULL;
1391                 struct object_entry *base_entry;
1392                 unsigned long used, used_0;
1393                 unsigned long avail;
1394                 off_t ofs;
1395                 unsigned char *buf, c;
1396
1397                 buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
1398
1399                 /*
1400                  * We want in_pack_type even if we do not reuse delta
1401                  * since non-delta representations could still be reused.
1402                  */
1403                 used = unpack_object_header_buffer(buf, avail,
1404                                                    &entry->in_pack_type,
1405                                                    &entry->size);
1406                 if (used == 0)
1407                         goto give_up;
1408
1409                 /*
1410                  * Determine if this is a delta and if so whether we can
1411                  * reuse it or not.  Otherwise let's find out as cheaply as
1412                  * possible what the actual type and size for this object is.
1413                  */
1414                 switch (entry->in_pack_type) {
1415                 default:
1416                         /* Not a delta hence we've already got all we need. */
1417                         entry->type = entry->in_pack_type;
1418                         entry->in_pack_header_size = used;
1419                         if (entry->type < OBJ_COMMIT || entry->type > OBJ_BLOB)
1420                                 goto give_up;
1421                         unuse_pack(&w_curs);
1422                         return;
1423                 case OBJ_REF_DELTA:
1424                         if (reuse_delta && !entry->preferred_base)
1425                                 base_ref = use_pack(p, &w_curs,
1426                                                 entry->in_pack_offset + used, NULL);
1427                         entry->in_pack_header_size = used + 20;
1428                         break;
1429                 case OBJ_OFS_DELTA:
1430                         buf = use_pack(p, &w_curs,
1431                                        entry->in_pack_offset + used, NULL);
1432                         used_0 = 0;
1433                         c = buf[used_0++];
1434                         ofs = c & 127;
1435                         while (c & 128) {
1436                                 ofs += 1;
1437                                 if (!ofs || MSB(ofs, 7)) {
1438                                         error("delta base offset overflow in pack for %s",
1439                                               oid_to_hex(&entry->idx.oid));
1440                                         goto give_up;
1441                                 }
1442                                 c = buf[used_0++];
1443                                 ofs = (ofs << 7) + (c & 127);
1444                         }
1445                         ofs = entry->in_pack_offset - ofs;
1446                         if (ofs <= 0 || ofs >= entry->in_pack_offset) {
1447                                 error("delta base offset out of bound for %s",
1448                                       oid_to_hex(&entry->idx.oid));
1449                                 goto give_up;
1450                         }
1451                         if (reuse_delta && !entry->preferred_base) {
1452                                 struct revindex_entry *revidx;
1453                                 revidx = find_pack_revindex(p, ofs);
1454                                 if (!revidx)
1455                                         goto give_up;
1456                                 base_ref = nth_packed_object_sha1(p, revidx->nr);
1457                         }
1458                         entry->in_pack_header_size = used + used_0;
1459                         break;
1460                 }
1461
1462                 if (base_ref && (base_entry = packlist_find(&to_pack, base_ref, NULL))) {
1463                         /*
1464                          * If base_ref was set above that means we wish to
1465                          * reuse delta data, and we even found that base
1466                          * in the list of objects we want to pack. Goodie!
1467                          *
1468                          * Depth value does not matter - find_deltas() will
1469                          * never consider reused delta as the base object to
1470                          * deltify other objects against, in order to avoid
1471                          * circular deltas.
1472                          */
1473                         entry->type = entry->in_pack_type;
1474                         entry->delta = base_entry;
1475                         entry->delta_size = entry->size;
1476                         entry->delta_sibling = base_entry->delta_child;
1477                         base_entry->delta_child = entry;
1478                         unuse_pack(&w_curs);
1479                         return;
1480                 }
1481
1482                 if (entry->type) {
1483                         /*
1484                          * This must be a delta and we already know what the
1485                          * final object type is.  Let's extract the actual
1486                          * object size from the delta header.
1487                          */
1488                         entry->size = get_size_from_delta(p, &w_curs,
1489                                         entry->in_pack_offset + entry->in_pack_header_size);
1490                         if (entry->size == 0)
1491                                 goto give_up;
1492                         unuse_pack(&w_curs);
1493                         return;
1494                 }
1495
1496                 /*
1497                  * No choice but to fall back to the recursive delta walk
1498                  * with sha1_object_info() to find about the object type
1499                  * at this point...
1500                  */
1501                 give_up:
1502                 unuse_pack(&w_curs);
1503         }
1504
1505         entry->type = sha1_object_info(entry->idx.oid.hash, &entry->size);
1506         /*
1507          * The error condition is checked in prepare_pack().  This is
1508          * to permit a missing preferred base object to be ignored
1509          * as a preferred base.  Doing so can result in a larger
1510          * pack file, but the transfer will still take place.
1511          */
1512 }
1513
1514 static int pack_offset_sort(const void *_a, const void *_b)
1515 {
1516         const struct object_entry *a = *(struct object_entry **)_a;
1517         const struct object_entry *b = *(struct object_entry **)_b;
1518
1519         /* avoid filesystem trashing with loose objects */
1520         if (!a->in_pack && !b->in_pack)
1521                 return oidcmp(&a->idx.oid, &b->idx.oid);
1522
1523         if (a->in_pack < b->in_pack)
1524                 return -1;
1525         if (a->in_pack > b->in_pack)
1526                 return 1;
1527         return a->in_pack_offset < b->in_pack_offset ? -1 :
1528                         (a->in_pack_offset > b->in_pack_offset);
1529 }
1530
1531 /*
1532  * Drop an on-disk delta we were planning to reuse. Naively, this would
1533  * just involve blanking out the "delta" field, but we have to deal
1534  * with some extra book-keeping:
1535  *
1536  *   1. Removing ourselves from the delta_sibling linked list.
1537  *
1538  *   2. Updating our size/type to the non-delta representation. These were
1539  *      either not recorded initially (size) or overwritten with the delta type
1540  *      (type) when check_object() decided to reuse the delta.
1541  *
1542  *   3. Resetting our delta depth, as we are now a base object.
1543  */
1544 static void drop_reused_delta(struct object_entry *entry)
1545 {
1546         struct object_entry **p = &entry->delta->delta_child;
1547         struct object_info oi = OBJECT_INFO_INIT;
1548
1549         while (*p) {
1550                 if (*p == entry)
1551                         *p = (*p)->delta_sibling;
1552                 else
1553                         p = &(*p)->delta_sibling;
1554         }
1555         entry->delta = NULL;
1556         entry->depth = 0;
1557
1558         oi.sizep = &entry->size;
1559         oi.typep = &entry->type;
1560         if (packed_object_info(entry->in_pack, entry->in_pack_offset, &oi) < 0) {
1561                 /*
1562                  * We failed to get the info from this pack for some reason;
1563                  * fall back to sha1_object_info, which may find another copy.
1564                  * And if that fails, the error will be recorded in entry->type
1565                  * and dealt with in prepare_pack().
1566                  */
1567                 entry->type = sha1_object_info(entry->idx.oid.hash,
1568                                                &entry->size);
1569         }
1570 }
1571
1572 /*
1573  * Follow the chain of deltas from this entry onward, throwing away any links
1574  * that cause us to hit a cycle (as determined by the DFS state flags in
1575  * the entries).
1576  *
1577  * We also detect too-long reused chains that would violate our --depth
1578  * limit.
1579  */
1580 static void break_delta_chains(struct object_entry *entry)
1581 {
1582         /*
1583          * The actual depth of each object we will write is stored as an int,
1584          * as it cannot exceed our int "depth" limit. But before we break
1585          * changes based no that limit, we may potentially go as deep as the
1586          * number of objects, which is elsewhere bounded to a uint32_t.
1587          */
1588         uint32_t total_depth;
1589         struct object_entry *cur, *next;
1590
1591         for (cur = entry, total_depth = 0;
1592              cur;
1593              cur = cur->delta, total_depth++) {
1594                 if (cur->dfs_state == DFS_DONE) {
1595                         /*
1596                          * We've already seen this object and know it isn't
1597                          * part of a cycle. We do need to append its depth
1598                          * to our count.
1599                          */
1600                         total_depth += cur->depth;
1601                         break;
1602                 }
1603
1604                 /*
1605                  * We break cycles before looping, so an ACTIVE state (or any
1606                  * other cruft which made its way into the state variable)
1607                  * is a bug.
1608                  */
1609                 if (cur->dfs_state != DFS_NONE)
1610                         die("BUG: confusing delta dfs state in first pass: %d",
1611                             cur->dfs_state);
1612
1613                 /*
1614                  * Now we know this is the first time we've seen the object. If
1615                  * it's not a delta, we're done traversing, but we'll mark it
1616                  * done to save time on future traversals.
1617                  */
1618                 if (!cur->delta) {
1619                         cur->dfs_state = DFS_DONE;
1620                         break;
1621                 }
1622
1623                 /*
1624                  * Mark ourselves as active and see if the next step causes
1625                  * us to cycle to another active object. It's important to do
1626                  * this _before_ we loop, because it impacts where we make the
1627                  * cut, and thus how our total_depth counter works.
1628                  * E.g., We may see a partial loop like:
1629                  *
1630                  *   A -> B -> C -> D -> B
1631                  *
1632                  * Cutting B->C breaks the cycle. But now the depth of A is
1633                  * only 1, and our total_depth counter is at 3. The size of the
1634                  * error is always one less than the size of the cycle we
1635                  * broke. Commits C and D were "lost" from A's chain.
1636                  *
1637                  * If we instead cut D->B, then the depth of A is correct at 3.
1638                  * We keep all commits in the chain that we examined.
1639                  */
1640                 cur->dfs_state = DFS_ACTIVE;
1641                 if (cur->delta->dfs_state == DFS_ACTIVE) {
1642                         drop_reused_delta(cur);
1643                         cur->dfs_state = DFS_DONE;
1644                         break;
1645                 }
1646         }
1647
1648         /*
1649          * And now that we've gone all the way to the bottom of the chain, we
1650          * need to clear the active flags and set the depth fields as
1651          * appropriate. Unlike the loop above, which can quit when it drops a
1652          * delta, we need to keep going to look for more depth cuts. So we need
1653          * an extra "next" pointer to keep going after we reset cur->delta.
1654          */
1655         for (cur = entry; cur; cur = next) {
1656                 next = cur->delta;
1657
1658                 /*
1659                  * We should have a chain of zero or more ACTIVE states down to
1660                  * a final DONE. We can quit after the DONE, because either it
1661                  * has no bases, or we've already handled them in a previous
1662                  * call.
1663                  */
1664                 if (cur->dfs_state == DFS_DONE)
1665                         break;
1666                 else if (cur->dfs_state != DFS_ACTIVE)
1667                         die("BUG: confusing delta dfs state in second pass: %d",
1668                             cur->dfs_state);
1669
1670                 /*
1671                  * If the total_depth is more than depth, then we need to snip
1672                  * the chain into two or more smaller chains that don't exceed
1673                  * the maximum depth. Most of the resulting chains will contain
1674                  * (depth + 1) entries (i.e., depth deltas plus one base), and
1675                  * the last chain (i.e., the one containing entry) will contain
1676                  * whatever entries are left over, namely
1677                  * (total_depth % (depth + 1)) of them.
1678                  *
1679                  * Since we are iterating towards decreasing depth, we need to
1680                  * decrement total_depth as we go, and we need to write to the
1681                  * entry what its final depth will be after all of the
1682                  * snipping. Since we're snipping into chains of length (depth
1683                  * + 1) entries, the final depth of an entry will be its
1684                  * original depth modulo (depth + 1). Any time we encounter an
1685                  * entry whose final depth is supposed to be zero, we snip it
1686                  * from its delta base, thereby making it so.
1687                  */
1688                 cur->depth = (total_depth--) % (depth + 1);
1689                 if (!cur->depth)
1690                         drop_reused_delta(cur);
1691
1692                 cur->dfs_state = DFS_DONE;
1693         }
1694 }
1695
1696 static void get_object_details(void)
1697 {
1698         uint32_t i;
1699         struct object_entry **sorted_by_offset;
1700
1701         sorted_by_offset = xcalloc(to_pack.nr_objects, sizeof(struct object_entry *));
1702         for (i = 0; i < to_pack.nr_objects; i++)
1703                 sorted_by_offset[i] = to_pack.objects + i;
1704         QSORT(sorted_by_offset, to_pack.nr_objects, pack_offset_sort);
1705
1706         for (i = 0; i < to_pack.nr_objects; i++) {
1707                 struct object_entry *entry = sorted_by_offset[i];
1708                 check_object(entry);
1709                 if (big_file_threshold < entry->size)
1710                         entry->no_try_delta = 1;
1711         }
1712
1713         /*
1714          * This must happen in a second pass, since we rely on the delta
1715          * information for the whole list being completed.
1716          */
1717         for (i = 0; i < to_pack.nr_objects; i++)
1718                 break_delta_chains(&to_pack.objects[i]);
1719
1720         free(sorted_by_offset);
1721 }
1722
1723 /*
1724  * We search for deltas in a list sorted by type, by filename hash, and then
1725  * by size, so that we see progressively smaller and smaller files.
1726  * That's because we prefer deltas to be from the bigger file
1727  * to the smaller -- deletes are potentially cheaper, but perhaps
1728  * more importantly, the bigger file is likely the more recent
1729  * one.  The deepest deltas are therefore the oldest objects which are
1730  * less susceptible to be accessed often.
1731  */
1732 static int type_size_sort(const void *_a, const void *_b)
1733 {
1734         const struct object_entry *a = *(struct object_entry **)_a;
1735         const struct object_entry *b = *(struct object_entry **)_b;
1736
1737         if (a->type > b->type)
1738                 return -1;
1739         if (a->type < b->type)
1740                 return 1;
1741         if (a->hash > b->hash)
1742                 return -1;
1743         if (a->hash < b->hash)
1744                 return 1;
1745         if (a->preferred_base > b->preferred_base)
1746                 return -1;
1747         if (a->preferred_base < b->preferred_base)
1748                 return 1;
1749         if (a->size > b->size)
1750                 return -1;
1751         if (a->size < b->size)
1752                 return 1;
1753         return a < b ? -1 : (a > b);  /* newest first */
1754 }
1755
1756 struct unpacked {
1757         struct object_entry *entry;
1758         void *data;
1759         struct delta_index *index;
1760         unsigned depth;
1761 };
1762
1763 static int delta_cacheable(unsigned long src_size, unsigned long trg_size,
1764                            unsigned long delta_size)
1765 {
1766         if (max_delta_cache_size && delta_cache_size + delta_size > max_delta_cache_size)
1767                 return 0;
1768
1769         if (delta_size < cache_max_small_delta_size)
1770                 return 1;
1771
1772         /* cache delta, if objects are large enough compared to delta size */
1773         if ((src_size >> 20) + (trg_size >> 21) > (delta_size >> 10))
1774                 return 1;
1775
1776         return 0;
1777 }
1778
1779 #ifndef NO_PTHREADS
1780
1781 static pthread_mutex_t read_mutex;
1782 #define read_lock()             pthread_mutex_lock(&read_mutex)
1783 #define read_unlock()           pthread_mutex_unlock(&read_mutex)
1784
1785 static pthread_mutex_t cache_mutex;
1786 #define cache_lock()            pthread_mutex_lock(&cache_mutex)
1787 #define cache_unlock()          pthread_mutex_unlock(&cache_mutex)
1788
1789 static pthread_mutex_t progress_mutex;
1790 #define progress_lock()         pthread_mutex_lock(&progress_mutex)
1791 #define progress_unlock()       pthread_mutex_unlock(&progress_mutex)
1792
1793 #else
1794
1795 #define read_lock()             (void)0
1796 #define read_unlock()           (void)0
1797 #define cache_lock()            (void)0
1798 #define cache_unlock()          (void)0
1799 #define progress_lock()         (void)0
1800 #define progress_unlock()       (void)0
1801
1802 #endif
1803
1804 static int try_delta(struct unpacked *trg, struct unpacked *src,
1805                      unsigned max_depth, unsigned long *mem_usage)
1806 {
1807         struct object_entry *trg_entry = trg->entry;
1808         struct object_entry *src_entry = src->entry;
1809         unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
1810         unsigned ref_depth;
1811         enum object_type type;
1812         void *delta_buf;
1813
1814         /* Don't bother doing diffs between different types */
1815         if (trg_entry->type != src_entry->type)
1816                 return -1;
1817
1818         /*
1819          * We do not bother to try a delta that we discarded on an
1820          * earlier try, but only when reusing delta data.  Note that
1821          * src_entry that is marked as the preferred_base should always
1822          * be considered, as even if we produce a suboptimal delta against
1823          * it, we will still save the transfer cost, as we already know
1824          * the other side has it and we won't send src_entry at all.
1825          */
1826         if (reuse_delta && trg_entry->in_pack &&
1827             trg_entry->in_pack == src_entry->in_pack &&
1828             !src_entry->preferred_base &&
1829             trg_entry->in_pack_type != OBJ_REF_DELTA &&
1830             trg_entry->in_pack_type != OBJ_OFS_DELTA)
1831                 return 0;
1832
1833         /* Let's not bust the allowed depth. */
1834         if (src->depth >= max_depth)
1835                 return 0;
1836
1837         /* Now some size filtering heuristics. */
1838         trg_size = trg_entry->size;
1839         if (!trg_entry->delta) {
1840                 max_size = trg_size/2 - 20;
1841                 ref_depth = 1;
1842         } else {
1843                 max_size = trg_entry->delta_size;
1844                 ref_depth = trg->depth;
1845         }
1846         max_size = (uint64_t)max_size * (max_depth - src->depth) /
1847                                                 (max_depth - ref_depth + 1);
1848         if (max_size == 0)
1849                 return 0;
1850         src_size = src_entry->size;
1851         sizediff = src_size < trg_size ? trg_size - src_size : 0;
1852         if (sizediff >= max_size)
1853                 return 0;
1854         if (trg_size < src_size / 32)
1855                 return 0;
1856
1857         /* Load data if not already done */
1858         if (!trg->data) {
1859                 read_lock();
1860                 trg->data = read_sha1_file(trg_entry->idx.oid.hash, &type,
1861                                            &sz);
1862                 read_unlock();
1863                 if (!trg->data)
1864                         die("object %s cannot be read",
1865                             oid_to_hex(&trg_entry->idx.oid));
1866                 if (sz != trg_size)
1867                         die("object %s inconsistent object length (%lu vs %lu)",
1868                             oid_to_hex(&trg_entry->idx.oid), sz,
1869                             trg_size);
1870                 *mem_usage += sz;
1871         }
1872         if (!src->data) {
1873                 read_lock();
1874                 src->data = read_sha1_file(src_entry->idx.oid.hash, &type,
1875                                            &sz);
1876                 read_unlock();
1877                 if (!src->data) {
1878                         if (src_entry->preferred_base) {
1879                                 static int warned = 0;
1880                                 if (!warned++)
1881                                         warning("object %s cannot be read",
1882                                                 oid_to_hex(&src_entry->idx.oid));
1883                                 /*
1884                                  * Those objects are not included in the
1885                                  * resulting pack.  Be resilient and ignore
1886                                  * them if they can't be read, in case the
1887                                  * pack could be created nevertheless.
1888                                  */
1889                                 return 0;
1890                         }
1891                         die("object %s cannot be read",
1892                             oid_to_hex(&src_entry->idx.oid));
1893                 }
1894                 if (sz != src_size)
1895                         die("object %s inconsistent object length (%lu vs %lu)",
1896                             oid_to_hex(&src_entry->idx.oid), sz,
1897                             src_size);
1898                 *mem_usage += sz;
1899         }
1900         if (!src->index) {
1901                 src->index = create_delta_index(src->data, src_size);
1902                 if (!src->index) {
1903                         static int warned = 0;
1904                         if (!warned++)
1905                                 warning("suboptimal pack - out of memory");
1906                         return 0;
1907                 }
1908                 *mem_usage += sizeof_delta_index(src->index);
1909         }
1910
1911         delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1912         if (!delta_buf)
1913                 return 0;
1914
1915         if (trg_entry->delta) {
1916                 /* Prefer only shallower same-sized deltas. */
1917                 if (delta_size == trg_entry->delta_size &&
1918                     src->depth + 1 >= trg->depth) {
1919                         free(delta_buf);
1920                         return 0;
1921                 }
1922         }
1923
1924         /*
1925          * Handle memory allocation outside of the cache
1926          * accounting lock.  Compiler will optimize the strangeness
1927          * away when NO_PTHREADS is defined.
1928          */
1929         free(trg_entry->delta_data);
1930         cache_lock();
1931         if (trg_entry->delta_data) {
1932                 delta_cache_size -= trg_entry->delta_size;
1933                 trg_entry->delta_data = NULL;
1934         }
1935         if (delta_cacheable(src_size, trg_size, delta_size)) {
1936                 delta_cache_size += delta_size;
1937                 cache_unlock();
1938                 trg_entry->delta_data = xrealloc(delta_buf, delta_size);
1939         } else {
1940                 cache_unlock();
1941                 free(delta_buf);
1942         }
1943
1944         trg_entry->delta = src_entry;
1945         trg_entry->delta_size = delta_size;
1946         trg->depth = src->depth + 1;
1947
1948         return 1;
1949 }
1950
1951 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
1952 {
1953         struct object_entry *child = me->delta_child;
1954         unsigned int m = n;
1955         while (child) {
1956                 unsigned int c = check_delta_limit(child, n + 1);
1957                 if (m < c)
1958                         m = c;
1959                 child = child->delta_sibling;
1960         }
1961         return m;
1962 }
1963
1964 static unsigned long free_unpacked(struct unpacked *n)
1965 {
1966         unsigned long freed_mem = sizeof_delta_index(n->index);
1967         free_delta_index(n->index);
1968         n->index = NULL;
1969         if (n->data) {
1970                 freed_mem += n->entry->size;
1971                 FREE_AND_NULL(n->data);
1972         }
1973         n->entry = NULL;
1974         n->depth = 0;
1975         return freed_mem;
1976 }
1977
1978 static void find_deltas(struct object_entry **list, unsigned *list_size,
1979                         int window, int depth, unsigned *processed)
1980 {
1981         uint32_t i, idx = 0, count = 0;
1982         struct unpacked *array;
1983         unsigned long mem_usage = 0;
1984
1985         array = xcalloc(window, sizeof(struct unpacked));
1986
1987         for (;;) {
1988                 struct object_entry *entry;
1989                 struct unpacked *n = array + idx;
1990                 int j, max_depth, best_base = -1;
1991
1992                 progress_lock();
1993                 if (!*list_size) {
1994                         progress_unlock();
1995                         break;
1996                 }
1997                 entry = *list++;
1998                 (*list_size)--;
1999                 if (!entry->preferred_base) {
2000                         (*processed)++;
2001                         display_progress(progress_state, *processed);
2002                 }
2003                 progress_unlock();
2004
2005                 mem_usage -= free_unpacked(n);
2006                 n->entry = entry;
2007
2008                 while (window_memory_limit &&
2009                        mem_usage > window_memory_limit &&
2010                        count > 1) {
2011                         uint32_t tail = (idx + window - count) % window;
2012                         mem_usage -= free_unpacked(array + tail);
2013                         count--;
2014                 }
2015
2016                 /* We do not compute delta to *create* objects we are not
2017                  * going to pack.
2018                  */
2019                 if (entry->preferred_base)
2020                         goto next;
2021
2022                 /*
2023                  * If the current object is at pack edge, take the depth the
2024                  * objects that depend on the current object into account
2025                  * otherwise they would become too deep.
2026                  */
2027                 max_depth = depth;
2028                 if (entry->delta_child) {
2029                         max_depth -= check_delta_limit(entry, 0);
2030                         if (max_depth <= 0)
2031                                 goto next;
2032                 }
2033
2034                 j = window;
2035                 while (--j > 0) {
2036                         int ret;
2037                         uint32_t other_idx = idx + j;
2038                         struct unpacked *m;
2039                         if (other_idx >= window)
2040                                 other_idx -= window;
2041                         m = array + other_idx;
2042                         if (!m->entry)
2043                                 break;
2044                         ret = try_delta(n, m, max_depth, &mem_usage);
2045                         if (ret < 0)
2046                                 break;
2047                         else if (ret > 0)
2048                                 best_base = other_idx;
2049                 }
2050
2051                 /*
2052                  * If we decided to cache the delta data, then it is best
2053                  * to compress it right away.  First because we have to do
2054                  * it anyway, and doing it here while we're threaded will
2055                  * save a lot of time in the non threaded write phase,
2056                  * as well as allow for caching more deltas within
2057                  * the same cache size limit.
2058                  * ...
2059                  * But only if not writing to stdout, since in that case
2060                  * the network is most likely throttling writes anyway,
2061                  * and therefore it is best to go to the write phase ASAP
2062                  * instead, as we can afford spending more time compressing
2063                  * between writes at that moment.
2064                  */
2065                 if (entry->delta_data && !pack_to_stdout) {
2066                         entry->z_delta_size = do_compress(&entry->delta_data,
2067                                                           entry->delta_size);
2068                         cache_lock();
2069                         delta_cache_size -= entry->delta_size;
2070                         delta_cache_size += entry->z_delta_size;
2071                         cache_unlock();
2072                 }
2073
2074                 /* if we made n a delta, and if n is already at max
2075                  * depth, leaving it in the window is pointless.  we
2076                  * should evict it first.
2077                  */
2078                 if (entry->delta && max_depth <= n->depth)
2079                         continue;
2080
2081                 /*
2082                  * Move the best delta base up in the window, after the
2083                  * currently deltified object, to keep it longer.  It will
2084                  * be the first base object to be attempted next.
2085                  */
2086                 if (entry->delta) {
2087                         struct unpacked swap = array[best_base];
2088                         int dist = (window + idx - best_base) % window;
2089                         int dst = best_base;
2090                         while (dist--) {
2091                                 int src = (dst + 1) % window;
2092                                 array[dst] = array[src];
2093                                 dst = src;
2094                         }
2095                         array[dst] = swap;
2096                 }
2097
2098                 next:
2099                 idx++;
2100                 if (count + 1 < window)
2101                         count++;
2102                 if (idx >= window)
2103                         idx = 0;
2104         }
2105
2106         for (i = 0; i < window; ++i) {
2107                 free_delta_index(array[i].index);
2108                 free(array[i].data);
2109         }
2110         free(array);
2111 }
2112
2113 #ifndef NO_PTHREADS
2114
2115 static void try_to_free_from_threads(size_t size)
2116 {
2117         read_lock();
2118         release_pack_memory(size);
2119         read_unlock();
2120 }
2121
2122 static try_to_free_t old_try_to_free_routine;
2123
2124 /*
2125  * The main thread waits on the condition that (at least) one of the workers
2126  * has stopped working (which is indicated in the .working member of
2127  * struct thread_params).
2128  * When a work thread has completed its work, it sets .working to 0 and
2129  * signals the main thread and waits on the condition that .data_ready
2130  * becomes 1.
2131  */
2132
2133 struct thread_params {
2134         pthread_t thread;
2135         struct object_entry **list;
2136         unsigned list_size;
2137         unsigned remaining;
2138         int window;
2139         int depth;
2140         int working;
2141         int data_ready;
2142         pthread_mutex_t mutex;
2143         pthread_cond_t cond;
2144         unsigned *processed;
2145 };
2146
2147 static pthread_cond_t progress_cond;
2148
2149 /*
2150  * Mutex and conditional variable can't be statically-initialized on Windows.
2151  */
2152 static void init_threaded_search(void)
2153 {
2154         init_recursive_mutex(&read_mutex);
2155         pthread_mutex_init(&cache_mutex, NULL);
2156         pthread_mutex_init(&progress_mutex, NULL);
2157         pthread_cond_init(&progress_cond, NULL);
2158         old_try_to_free_routine = set_try_to_free_routine(try_to_free_from_threads);
2159 }
2160
2161 static void cleanup_threaded_search(void)
2162 {
2163         set_try_to_free_routine(old_try_to_free_routine);
2164         pthread_cond_destroy(&progress_cond);
2165         pthread_mutex_destroy(&read_mutex);
2166         pthread_mutex_destroy(&cache_mutex);
2167         pthread_mutex_destroy(&progress_mutex);
2168 }
2169
2170 static void *threaded_find_deltas(void *arg)
2171 {
2172         struct thread_params *me = arg;
2173
2174         progress_lock();
2175         while (me->remaining) {
2176                 progress_unlock();
2177
2178                 find_deltas(me->list, &me->remaining,
2179                             me->window, me->depth, me->processed);
2180
2181                 progress_lock();
2182                 me->working = 0;
2183                 pthread_cond_signal(&progress_cond);
2184                 progress_unlock();
2185
2186                 /*
2187                  * We must not set ->data_ready before we wait on the
2188                  * condition because the main thread may have set it to 1
2189                  * before we get here. In order to be sure that new
2190                  * work is available if we see 1 in ->data_ready, it
2191                  * was initialized to 0 before this thread was spawned
2192                  * and we reset it to 0 right away.
2193                  */
2194                 pthread_mutex_lock(&me->mutex);
2195                 while (!me->data_ready)
2196                         pthread_cond_wait(&me->cond, &me->mutex);
2197                 me->data_ready = 0;
2198                 pthread_mutex_unlock(&me->mutex);
2199
2200                 progress_lock();
2201         }
2202         progress_unlock();
2203         /* leave ->working 1 so that this doesn't get more work assigned */
2204         return NULL;
2205 }
2206
2207 static void ll_find_deltas(struct object_entry **list, unsigned list_size,
2208                            int window, int depth, unsigned *processed)
2209 {
2210         struct thread_params *p;
2211         int i, ret, active_threads = 0;
2212
2213         init_threaded_search();
2214
2215         if (delta_search_threads <= 1) {
2216                 find_deltas(list, &list_size, window, depth, processed);
2217                 cleanup_threaded_search();
2218                 return;
2219         }
2220         if (progress > pack_to_stdout)
2221                 fprintf(stderr, "Delta compression using up to %d threads.\n",
2222                                 delta_search_threads);
2223         p = xcalloc(delta_search_threads, sizeof(*p));
2224
2225         /* Partition the work amongst work threads. */
2226         for (i = 0; i < delta_search_threads; i++) {
2227                 unsigned sub_size = list_size / (delta_search_threads - i);
2228
2229                 /* don't use too small segments or no deltas will be found */
2230                 if (sub_size < 2*window && i+1 < delta_search_threads)
2231                         sub_size = 0;
2232
2233                 p[i].window = window;
2234                 p[i].depth = depth;
2235                 p[i].processed = processed;
2236                 p[i].working = 1;
2237                 p[i].data_ready = 0;
2238
2239                 /* try to split chunks on "path" boundaries */
2240                 while (sub_size && sub_size < list_size &&
2241                        list[sub_size]->hash &&
2242                        list[sub_size]->hash == list[sub_size-1]->hash)
2243                         sub_size++;
2244
2245                 p[i].list = list;
2246                 p[i].list_size = sub_size;
2247                 p[i].remaining = sub_size;
2248
2249                 list += sub_size;
2250                 list_size -= sub_size;
2251         }
2252
2253         /* Start work threads. */
2254         for (i = 0; i < delta_search_threads; i++) {
2255                 if (!p[i].list_size)
2256                         continue;
2257                 pthread_mutex_init(&p[i].mutex, NULL);
2258                 pthread_cond_init(&p[i].cond, NULL);
2259                 ret = pthread_create(&p[i].thread, NULL,
2260                                      threaded_find_deltas, &p[i]);
2261                 if (ret)
2262                         die("unable to create thread: %s", strerror(ret));
2263                 active_threads++;
2264         }
2265
2266         /*
2267          * Now let's wait for work completion.  Each time a thread is done
2268          * with its work, we steal half of the remaining work from the
2269          * thread with the largest number of unprocessed objects and give
2270          * it to that newly idle thread.  This ensure good load balancing
2271          * until the remaining object list segments are simply too short
2272          * to be worth splitting anymore.
2273          */
2274         while (active_threads) {
2275                 struct thread_params *target = NULL;
2276                 struct thread_params *victim = NULL;
2277                 unsigned sub_size = 0;
2278
2279                 progress_lock();
2280                 for (;;) {
2281                         for (i = 0; !target && i < delta_search_threads; i++)
2282                                 if (!p[i].working)
2283                                         target = &p[i];
2284                         if (target)
2285                                 break;
2286                         pthread_cond_wait(&progress_cond, &progress_mutex);
2287                 }
2288
2289                 for (i = 0; i < delta_search_threads; i++)
2290                         if (p[i].remaining > 2*window &&
2291                             (!victim || victim->remaining < p[i].remaining))
2292                                 victim = &p[i];
2293                 if (victim) {
2294                         sub_size = victim->remaining / 2;
2295                         list = victim->list + victim->list_size - sub_size;
2296                         while (sub_size && list[0]->hash &&
2297                                list[0]->hash == list[-1]->hash) {
2298                                 list++;
2299                                 sub_size--;
2300                         }
2301                         if (!sub_size) {
2302                                 /*
2303                                  * It is possible for some "paths" to have
2304                                  * so many objects that no hash boundary
2305                                  * might be found.  Let's just steal the
2306                                  * exact half in that case.
2307                                  */
2308                                 sub_size = victim->remaining / 2;
2309                                 list -= sub_size;
2310                         }
2311                         target->list = list;
2312                         victim->list_size -= sub_size;
2313                         victim->remaining -= sub_size;
2314                 }
2315                 target->list_size = sub_size;
2316                 target->remaining = sub_size;
2317                 target->working = 1;
2318                 progress_unlock();
2319
2320                 pthread_mutex_lock(&target->mutex);
2321                 target->data_ready = 1;
2322                 pthread_cond_signal(&target->cond);
2323                 pthread_mutex_unlock(&target->mutex);
2324
2325                 if (!sub_size) {
2326                         pthread_join(target->thread, NULL);
2327                         pthread_cond_destroy(&target->cond);
2328                         pthread_mutex_destroy(&target->mutex);
2329                         active_threads--;
2330                 }
2331         }
2332         cleanup_threaded_search();
2333         free(p);
2334 }
2335
2336 #else
2337 #define ll_find_deltas(l, s, w, d, p)   find_deltas(l, &s, w, d, p)
2338 #endif
2339
2340 static void add_tag_chain(const struct object_id *oid)
2341 {
2342         struct tag *tag;
2343
2344         /*
2345          * We catch duplicates already in add_object_entry(), but we'd
2346          * prefer to do this extra check to avoid having to parse the
2347          * tag at all if we already know that it's being packed (e.g., if
2348          * it was included via bitmaps, we would not have parsed it
2349          * previously).
2350          */
2351         if (packlist_find(&to_pack, oid->hash, NULL))
2352                 return;
2353
2354         tag = lookup_tag(oid);
2355         while (1) {
2356                 if (!tag || parse_tag(tag) || !tag->tagged)
2357                         die("unable to pack objects reachable from tag %s",
2358                             oid_to_hex(oid));
2359
2360                 add_object_entry(tag->object.oid.hash, OBJ_TAG, NULL, 0);
2361
2362                 if (tag->tagged->type != OBJ_TAG)
2363                         return;
2364
2365                 tag = (struct tag *)tag->tagged;
2366         }
2367 }
2368
2369 static int add_ref_tag(const char *path, const struct object_id *oid, int flag, void *cb_data)
2370 {
2371         struct object_id peeled;
2372
2373         if (starts_with(path, "refs/tags/") && /* is a tag? */
2374             !peel_ref(path, peeled.hash)    && /* peelable? */
2375             packlist_find(&to_pack, peeled.hash, NULL))      /* object packed? */
2376                 add_tag_chain(oid);
2377         return 0;
2378 }
2379
2380 static void prepare_pack(int window, int depth)
2381 {
2382         struct object_entry **delta_list;
2383         uint32_t i, nr_deltas;
2384         unsigned n;
2385
2386         get_object_details();
2387
2388         /*
2389          * If we're locally repacking then we need to be doubly careful
2390          * from now on in order to make sure no stealth corruption gets
2391          * propagated to the new pack.  Clients receiving streamed packs
2392          * should validate everything they get anyway so no need to incur
2393          * the additional cost here in that case.
2394          */
2395         if (!pack_to_stdout)
2396                 do_check_packed_object_crc = 1;
2397
2398         if (!to_pack.nr_objects || !window || !depth)
2399                 return;
2400
2401         ALLOC_ARRAY(delta_list, to_pack.nr_objects);
2402         nr_deltas = n = 0;
2403
2404         for (i = 0; i < to_pack.nr_objects; i++) {
2405                 struct object_entry *entry = to_pack.objects + i;
2406
2407                 if (entry->delta)
2408                         /* This happens if we decided to reuse existing
2409                          * delta from a pack.  "reuse_delta &&" is implied.
2410                          */
2411                         continue;
2412
2413                 if (entry->size < 50)
2414                         continue;
2415
2416                 if (entry->no_try_delta)
2417                         continue;
2418
2419                 if (!entry->preferred_base) {
2420                         nr_deltas++;
2421                         if (entry->type < 0)
2422                                 die("unable to get type of object %s",
2423                                     oid_to_hex(&entry->idx.oid));
2424                 } else {
2425                         if (entry->type < 0) {
2426                                 /*
2427                                  * This object is not found, but we
2428                                  * don't have to include it anyway.
2429                                  */
2430                                 continue;
2431                         }
2432                 }
2433
2434                 delta_list[n++] = entry;
2435         }
2436
2437         if (nr_deltas && n > 1) {
2438                 unsigned nr_done = 0;
2439                 if (progress)
2440                         progress_state = start_progress(_("Compressing objects"),
2441                                                         nr_deltas);
2442                 QSORT(delta_list, n, type_size_sort);
2443                 ll_find_deltas(delta_list, n, window+1, depth, &nr_done);
2444                 stop_progress(&progress_state);
2445                 if (nr_done != nr_deltas)
2446                         die("inconsistency with delta count");
2447         }
2448         free(delta_list);
2449 }
2450
2451 static int git_pack_config(const char *k, const char *v, void *cb)
2452 {
2453         if (!strcmp(k, "pack.window")) {
2454                 window = git_config_int(k, v);
2455                 return 0;
2456         }
2457         if (!strcmp(k, "pack.windowmemory")) {
2458                 window_memory_limit = git_config_ulong(k, v);
2459                 return 0;
2460         }
2461         if (!strcmp(k, "pack.depth")) {
2462                 depth = git_config_int(k, v);
2463                 return 0;
2464         }
2465         if (!strcmp(k, "pack.deltacachesize")) {
2466                 max_delta_cache_size = git_config_int(k, v);
2467                 return 0;
2468         }
2469         if (!strcmp(k, "pack.deltacachelimit")) {
2470                 cache_max_small_delta_size = git_config_int(k, v);
2471                 return 0;
2472         }
2473         if (!strcmp(k, "pack.writebitmaphashcache")) {
2474                 if (git_config_bool(k, v))
2475                         write_bitmap_options |= BITMAP_OPT_HASH_CACHE;
2476                 else
2477                         write_bitmap_options &= ~BITMAP_OPT_HASH_CACHE;
2478         }
2479         if (!strcmp(k, "pack.usebitmaps")) {
2480                 use_bitmap_index_default = git_config_bool(k, v);
2481                 return 0;
2482         }
2483         if (!strcmp(k, "pack.threads")) {
2484                 delta_search_threads = git_config_int(k, v);
2485                 if (delta_search_threads < 0)
2486                         die("invalid number of threads specified (%d)",
2487                             delta_search_threads);
2488 #ifdef NO_PTHREADS
2489                 if (delta_search_threads != 1) {
2490                         warning("no threads support, ignoring %s", k);
2491                         delta_search_threads = 0;
2492                 }
2493 #endif
2494                 return 0;
2495         }
2496         if (!strcmp(k, "pack.indexversion")) {
2497                 pack_idx_opts.version = git_config_int(k, v);
2498                 if (pack_idx_opts.version > 2)
2499                         die("bad pack.indexversion=%"PRIu32,
2500                             pack_idx_opts.version);
2501                 return 0;
2502         }
2503         return git_default_config(k, v, cb);
2504 }
2505
2506 static void read_object_list_from_stdin(void)
2507 {
2508         char line[40 + 1 + PATH_MAX + 2];
2509         unsigned char sha1[20];
2510
2511         for (;;) {
2512                 if (!fgets(line, sizeof(line), stdin)) {
2513                         if (feof(stdin))
2514                                 break;
2515                         if (!ferror(stdin))
2516                                 die("fgets returned NULL, not EOF, not error!");
2517                         if (errno != EINTR)
2518                                 die_errno("fgets");
2519                         clearerr(stdin);
2520                         continue;
2521                 }
2522                 if (line[0] == '-') {
2523                         if (get_sha1_hex(line+1, sha1))
2524                                 die("expected edge sha1, got garbage:\n %s",
2525                                     line);
2526                         add_preferred_base(sha1);
2527                         continue;
2528                 }
2529                 if (get_sha1_hex(line, sha1))
2530                         die("expected sha1, got garbage:\n %s", line);
2531
2532                 add_preferred_base_object(line+41);
2533                 add_object_entry(sha1, 0, line+41, 0);
2534         }
2535 }
2536
2537 #define OBJECT_ADDED (1u<<20)
2538
2539 static void show_commit(struct commit *commit, void *data)
2540 {
2541         add_object_entry(commit->object.oid.hash, OBJ_COMMIT, NULL, 0);
2542         commit->object.flags |= OBJECT_ADDED;
2543
2544         if (write_bitmap_index)
2545                 index_commit_for_bitmap(commit);
2546 }
2547
2548 static void show_object(struct object *obj, const char *name, void *data)
2549 {
2550         add_preferred_base_object(name);
2551         add_object_entry(obj->oid.hash, obj->type, name, 0);
2552         obj->flags |= OBJECT_ADDED;
2553 }
2554
2555 static void show_edge(struct commit *commit)
2556 {
2557         add_preferred_base(commit->object.oid.hash);
2558 }
2559
2560 struct in_pack_object {
2561         off_t offset;
2562         struct object *object;
2563 };
2564
2565 struct in_pack {
2566         unsigned int alloc;
2567         unsigned int nr;
2568         struct in_pack_object *array;
2569 };
2570
2571 static void mark_in_pack_object(struct object *object, struct packed_git *p, struct in_pack *in_pack)
2572 {
2573         in_pack->array[in_pack->nr].offset = find_pack_entry_one(object->oid.hash, p);
2574         in_pack->array[in_pack->nr].object = object;
2575         in_pack->nr++;
2576 }
2577
2578 /*
2579  * Compare the objects in the offset order, in order to emulate the
2580  * "git rev-list --objects" output that produced the pack originally.
2581  */
2582 static int ofscmp(const void *a_, const void *b_)
2583 {
2584         struct in_pack_object *a = (struct in_pack_object *)a_;
2585         struct in_pack_object *b = (struct in_pack_object *)b_;
2586
2587         if (a->offset < b->offset)
2588                 return -1;
2589         else if (a->offset > b->offset)
2590                 return 1;
2591         else
2592                 return oidcmp(&a->object->oid, &b->object->oid);
2593 }
2594
2595 static void add_objects_in_unpacked_packs(struct rev_info *revs)
2596 {
2597         struct packed_git *p;
2598         struct in_pack in_pack;
2599         uint32_t i;
2600
2601         memset(&in_pack, 0, sizeof(in_pack));
2602
2603         for (p = packed_git; p; p = p->next) {
2604                 const unsigned char *sha1;
2605                 struct object *o;
2606
2607                 if (!p->pack_local || p->pack_keep)
2608                         continue;
2609                 if (open_pack_index(p))
2610                         die("cannot open pack index");
2611
2612                 ALLOC_GROW(in_pack.array,
2613                            in_pack.nr + p->num_objects,
2614                            in_pack.alloc);
2615
2616                 for (i = 0; i < p->num_objects; i++) {
2617                         sha1 = nth_packed_object_sha1(p, i);
2618                         o = lookup_unknown_object(sha1);
2619                         if (!(o->flags & OBJECT_ADDED))
2620                                 mark_in_pack_object(o, p, &in_pack);
2621                         o->flags |= OBJECT_ADDED;
2622                 }
2623         }
2624
2625         if (in_pack.nr) {
2626                 QSORT(in_pack.array, in_pack.nr, ofscmp);
2627                 for (i = 0; i < in_pack.nr; i++) {
2628                         struct object *o = in_pack.array[i].object;
2629                         add_object_entry(o->oid.hash, o->type, "", 0);
2630                 }
2631         }
2632         free(in_pack.array);
2633 }
2634
2635 static int add_loose_object(const struct object_id *oid, const char *path,
2636                             void *data)
2637 {
2638         enum object_type type = sha1_object_info(oid->hash, NULL);
2639
2640         if (type < 0) {
2641                 warning("loose object at %s could not be examined", path);
2642                 return 0;
2643         }
2644
2645         add_object_entry(oid->hash, type, "", 0);
2646         return 0;
2647 }
2648
2649 /*
2650  * We actually don't even have to worry about reachability here.
2651  * add_object_entry will weed out duplicates, so we just add every
2652  * loose object we find.
2653  */
2654 static void add_unreachable_loose_objects(void)
2655 {
2656         for_each_loose_file_in_objdir(get_object_directory(),
2657                                       add_loose_object,
2658                                       NULL, NULL, NULL);
2659 }
2660
2661 static int has_sha1_pack_kept_or_nonlocal(const unsigned char *sha1)
2662 {
2663         static struct packed_git *last_found = (void *)1;
2664         struct packed_git *p;
2665
2666         p = (last_found != (void *)1) ? last_found : packed_git;
2667
2668         while (p) {
2669                 if ((!p->pack_local || p->pack_keep) &&
2670                         find_pack_entry_one(sha1, p)) {
2671                         last_found = p;
2672                         return 1;
2673                 }
2674                 if (p == last_found)
2675                         p = packed_git;
2676                 else
2677                         p = p->next;
2678                 if (p == last_found)
2679                         p = p->next;
2680         }
2681         return 0;
2682 }
2683
2684 /*
2685  * Store a list of sha1s that are should not be discarded
2686  * because they are either written too recently, or are
2687  * reachable from another object that was.
2688  *
2689  * This is filled by get_object_list.
2690  */
2691 static struct oid_array recent_objects;
2692
2693 static int loosened_object_can_be_discarded(const struct object_id *oid,
2694                                             timestamp_t mtime)
2695 {
2696         if (!unpack_unreachable_expiration)
2697                 return 0;
2698         if (mtime > unpack_unreachable_expiration)
2699                 return 0;
2700         if (oid_array_lookup(&recent_objects, oid) >= 0)
2701                 return 0;
2702         return 1;
2703 }
2704
2705 static void loosen_unused_packed_objects(struct rev_info *revs)
2706 {
2707         struct packed_git *p;
2708         uint32_t i;
2709         struct object_id oid;
2710
2711         for (p = packed_git; p; p = p->next) {
2712                 if (!p->pack_local || p->pack_keep)
2713                         continue;
2714
2715                 if (open_pack_index(p))
2716                         die("cannot open pack index");
2717
2718                 for (i = 0; i < p->num_objects; i++) {
2719                         nth_packed_object_oid(&oid, p, i);
2720                         if (!packlist_find(&to_pack, oid.hash, NULL) &&
2721                             !has_sha1_pack_kept_or_nonlocal(oid.hash) &&
2722                             !loosened_object_can_be_discarded(&oid, p->mtime))
2723                                 if (force_object_loose(oid.hash, p->mtime))
2724                                         die("unable to force loose object");
2725                 }
2726         }
2727 }
2728
2729 /*
2730  * This tracks any options which pack-reuse code expects to be on, or which a
2731  * reader of the pack might not understand, and which would therefore prevent
2732  * blind reuse of what we have on disk.
2733  */
2734 static int pack_options_allow_reuse(void)
2735 {
2736         return pack_to_stdout &&
2737                allow_ofs_delta &&
2738                !ignore_packed_keep &&
2739                (!local || !have_non_local_packs) &&
2740                !incremental;
2741 }
2742
2743 static int get_object_list_from_bitmap(struct rev_info *revs)
2744 {
2745         if (prepare_bitmap_walk(revs) < 0)
2746                 return -1;
2747
2748         if (pack_options_allow_reuse() &&
2749             !reuse_partial_packfile_from_bitmap(
2750                         &reuse_packfile,
2751                         &reuse_packfile_objects,
2752                         &reuse_packfile_offset)) {
2753                 assert(reuse_packfile_objects);
2754                 nr_result += reuse_packfile_objects;
2755                 display_progress(progress_state, nr_result);
2756         }
2757
2758         traverse_bitmap_commit_list(&add_object_entry_from_bitmap);
2759         return 0;
2760 }
2761
2762 static void record_recent_object(struct object *obj,
2763                                  const char *name,
2764                                  void *data)
2765 {
2766         oid_array_append(&recent_objects, &obj->oid);
2767 }
2768
2769 static void record_recent_commit(struct commit *commit, void *data)
2770 {
2771         oid_array_append(&recent_objects, &commit->object.oid);
2772 }
2773
2774 static void get_object_list(int ac, const char **av)
2775 {
2776         struct rev_info revs;
2777         char line[1000];
2778         int flags = 0;
2779
2780         init_revisions(&revs, NULL);
2781         save_commit_buffer = 0;
2782         setup_revisions(ac, av, &revs, NULL);
2783
2784         /* make sure shallows are read */
2785         is_repository_shallow();
2786
2787         while (fgets(line, sizeof(line), stdin) != NULL) {
2788                 int len = strlen(line);
2789                 if (len && line[len - 1] == '\n')
2790                         line[--len] = 0;
2791                 if (!len)
2792                         break;
2793                 if (*line == '-') {
2794                         if (!strcmp(line, "--not")) {
2795                                 flags ^= UNINTERESTING;
2796                                 write_bitmap_index = 0;
2797                                 continue;
2798                         }
2799                         if (starts_with(line, "--shallow ")) {
2800                                 struct object_id oid;
2801                                 if (get_oid_hex(line + 10, &oid))
2802                                         die("not an SHA-1 '%s'", line + 10);
2803                                 register_shallow(&oid);
2804                                 use_bitmap_index = 0;
2805                                 continue;
2806                         }
2807                         die("not a rev '%s'", line);
2808                 }
2809                 if (handle_revision_arg(line, &revs, flags, REVARG_CANNOT_BE_FILENAME))
2810                         die("bad revision '%s'", line);
2811         }
2812
2813         if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
2814                 return;
2815
2816         if (prepare_revision_walk(&revs))
2817                 die("revision walk setup failed");
2818         mark_edges_uninteresting(&revs, show_edge);
2819         traverse_commit_list(&revs, show_commit, show_object, NULL);
2820
2821         if (unpack_unreachable_expiration) {
2822                 revs.ignore_missing_links = 1;
2823                 if (add_unseen_recent_objects_to_traversal(&revs,
2824                                 unpack_unreachable_expiration))
2825                         die("unable to add recent objects");
2826                 if (prepare_revision_walk(&revs))
2827                         die("revision walk setup failed");
2828                 traverse_commit_list(&revs, record_recent_commit,
2829                                      record_recent_object, NULL);
2830         }
2831
2832         if (keep_unreachable)
2833                 add_objects_in_unpacked_packs(&revs);
2834         if (pack_loose_unreachable)
2835                 add_unreachable_loose_objects();
2836         if (unpack_unreachable)
2837                 loosen_unused_packed_objects(&revs);
2838
2839         oid_array_clear(&recent_objects);
2840 }
2841
2842 static int option_parse_index_version(const struct option *opt,
2843                                       const char *arg, int unset)
2844 {
2845         char *c;
2846         const char *val = arg;
2847         pack_idx_opts.version = strtoul(val, &c, 10);
2848         if (pack_idx_opts.version > 2)
2849                 die(_("unsupported index version %s"), val);
2850         if (*c == ',' && c[1])
2851                 pack_idx_opts.off32_limit = strtoul(c+1, &c, 0);
2852         if (*c || pack_idx_opts.off32_limit & 0x80000000)
2853                 die(_("bad index version '%s'"), val);
2854         return 0;
2855 }
2856
2857 static int option_parse_unpack_unreachable(const struct option *opt,
2858                                            const char *arg, int unset)
2859 {
2860         if (unset) {
2861                 unpack_unreachable = 0;
2862                 unpack_unreachable_expiration = 0;
2863         }
2864         else {
2865                 unpack_unreachable = 1;
2866                 if (arg)
2867                         unpack_unreachable_expiration = approxidate(arg);
2868         }
2869         return 0;
2870 }
2871
2872 int cmd_pack_objects(int argc, const char **argv, const char *prefix)
2873 {
2874         int use_internal_rev_list = 0;
2875         int thin = 0;
2876         int shallow = 0;
2877         int all_progress_implied = 0;
2878         struct argv_array rp = ARGV_ARRAY_INIT;
2879         int rev_list_unpacked = 0, rev_list_all = 0, rev_list_reflog = 0;
2880         int rev_list_index = 0;
2881         struct option pack_objects_options[] = {
2882                 OPT_SET_INT('q', "quiet", &progress,
2883                             N_("do not show progress meter"), 0),
2884                 OPT_SET_INT(0, "progress", &progress,
2885                             N_("show progress meter"), 1),
2886                 OPT_SET_INT(0, "all-progress", &progress,
2887                             N_("show progress meter during object writing phase"), 2),
2888                 OPT_BOOL(0, "all-progress-implied",
2889                          &all_progress_implied,
2890                          N_("similar to --all-progress when progress meter is shown")),
2891                 { OPTION_CALLBACK, 0, "index-version", NULL, N_("version[,offset]"),
2892                   N_("write the pack index file in the specified idx format version"),
2893                   0, option_parse_index_version },
2894                 OPT_MAGNITUDE(0, "max-pack-size", &pack_size_limit,
2895                               N_("maximum size of each output pack file")),
2896                 OPT_BOOL(0, "local", &local,
2897                          N_("ignore borrowed objects from alternate object store")),
2898                 OPT_BOOL(0, "incremental", &incremental,
2899                          N_("ignore packed objects")),
2900                 OPT_INTEGER(0, "window", &window,
2901                             N_("limit pack window by objects")),
2902                 OPT_MAGNITUDE(0, "window-memory", &window_memory_limit,
2903                               N_("limit pack window by memory in addition to object limit")),
2904                 OPT_INTEGER(0, "depth", &depth,
2905                             N_("maximum length of delta chain allowed in the resulting pack")),
2906                 OPT_BOOL(0, "reuse-delta", &reuse_delta,
2907                          N_("reuse existing deltas")),
2908                 OPT_BOOL(0, "reuse-object", &reuse_object,
2909                          N_("reuse existing objects")),
2910                 OPT_BOOL(0, "delta-base-offset", &allow_ofs_delta,
2911                          N_("use OFS_DELTA objects")),
2912                 OPT_INTEGER(0, "threads", &delta_search_threads,
2913                             N_("use threads when searching for best delta matches")),
2914                 OPT_BOOL(0, "non-empty", &non_empty,
2915                          N_("do not create an empty pack output")),
2916                 OPT_BOOL(0, "revs", &use_internal_rev_list,
2917                          N_("read revision arguments from standard input")),
2918                 { OPTION_SET_INT, 0, "unpacked", &rev_list_unpacked, NULL,
2919                   N_("limit the objects to those that are not yet packed"),
2920                   PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
2921                 { OPTION_SET_INT, 0, "all", &rev_list_all, NULL,
2922                   N_("include objects reachable from any reference"),
2923                   PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
2924                 { OPTION_SET_INT, 0, "reflog", &rev_list_reflog, NULL,
2925                   N_("include objects referred by reflog entries"),
2926                   PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
2927                 { OPTION_SET_INT, 0, "indexed-objects", &rev_list_index, NULL,
2928                   N_("include objects referred to by the index"),
2929                   PARSE_OPT_NOARG | PARSE_OPT_NONEG, NULL, 1 },
2930                 OPT_BOOL(0, "stdout", &pack_to_stdout,
2931                          N_("output pack to stdout")),
2932                 OPT_BOOL(0, "include-tag", &include_tag,
2933                          N_("include tag objects that refer to objects to be packed")),
2934                 OPT_BOOL(0, "keep-unreachable", &keep_unreachable,
2935                          N_("keep unreachable objects")),
2936                 OPT_BOOL(0, "pack-loose-unreachable", &pack_loose_unreachable,
2937                          N_("pack loose unreachable objects")),
2938                 { OPTION_CALLBACK, 0, "unpack-unreachable", NULL, N_("time"),
2939                   N_("unpack unreachable objects newer than <time>"),
2940                   PARSE_OPT_OPTARG, option_parse_unpack_unreachable },
2941                 OPT_BOOL(0, "thin", &thin,
2942                          N_("create thin packs")),
2943                 OPT_BOOL(0, "shallow", &shallow,
2944                          N_("create packs suitable for shallow fetches")),
2945                 OPT_BOOL(0, "honor-pack-keep", &ignore_packed_keep,
2946                          N_("ignore packs that have companion .keep file")),
2947                 OPT_INTEGER(0, "compression", &pack_compression_level,
2948                             N_("pack compression level")),
2949                 OPT_SET_INT(0, "keep-true-parents", &grafts_replace_parents,
2950                             N_("do not hide commits by grafts"), 0),
2951                 OPT_BOOL(0, "use-bitmap-index", &use_bitmap_index,
2952                          N_("use a bitmap index if available to speed up counting objects")),
2953                 OPT_BOOL(0, "write-bitmap-index", &write_bitmap_index,
2954                          N_("write a bitmap index together with the pack index")),
2955                 OPT_END(),
2956         };
2957
2958         check_replace_refs = 0;
2959
2960         reset_pack_idx_option(&pack_idx_opts);
2961         git_config(git_pack_config, NULL);
2962
2963         progress = isatty(2);
2964         argc = parse_options(argc, argv, prefix, pack_objects_options,
2965                              pack_usage, 0);
2966
2967         if (argc) {
2968                 base_name = argv[0];
2969                 argc--;
2970         }
2971         if (pack_to_stdout != !base_name || argc)
2972                 usage_with_options(pack_usage, pack_objects_options);
2973
2974         argv_array_push(&rp, "pack-objects");
2975         if (thin) {
2976                 use_internal_rev_list = 1;
2977                 argv_array_push(&rp, shallow
2978                                 ? "--objects-edge-aggressive"
2979                                 : "--objects-edge");
2980         } else
2981                 argv_array_push(&rp, "--objects");
2982
2983         if (rev_list_all) {
2984                 use_internal_rev_list = 1;
2985                 argv_array_push(&rp, "--all");
2986         }
2987         if (rev_list_reflog) {
2988                 use_internal_rev_list = 1;
2989                 argv_array_push(&rp, "--reflog");
2990         }
2991         if (rev_list_index) {
2992                 use_internal_rev_list = 1;
2993                 argv_array_push(&rp, "--indexed-objects");
2994         }
2995         if (rev_list_unpacked) {
2996                 use_internal_rev_list = 1;
2997                 argv_array_push(&rp, "--unpacked");
2998         }
2999
3000         if (!reuse_object)
3001                 reuse_delta = 0;
3002         if (pack_compression_level == -1)
3003                 pack_compression_level = Z_DEFAULT_COMPRESSION;
3004         else if (pack_compression_level < 0 || pack_compression_level > Z_BEST_COMPRESSION)
3005                 die("bad pack compression level %d", pack_compression_level);
3006
3007         if (!delta_search_threads)      /* --threads=0 means autodetect */
3008                 delta_search_threads = online_cpus();
3009
3010 #ifdef NO_PTHREADS
3011         if (delta_search_threads != 1)
3012                 warning("no threads support, ignoring --threads");
3013 #endif
3014         if (!pack_to_stdout && !pack_size_limit)
3015                 pack_size_limit = pack_size_limit_cfg;
3016         if (pack_to_stdout && pack_size_limit)
3017                 die("--max-pack-size cannot be used to build a pack for transfer.");
3018         if (pack_size_limit && pack_size_limit < 1024*1024) {
3019                 warning("minimum pack size limit is 1 MiB");
3020                 pack_size_limit = 1024*1024;
3021         }
3022
3023         if (!pack_to_stdout && thin)
3024                 die("--thin cannot be used to build an indexable pack.");
3025
3026         if (keep_unreachable && unpack_unreachable)
3027                 die("--keep-unreachable and --unpack-unreachable are incompatible.");
3028         if (!rev_list_all || !rev_list_reflog || !rev_list_index)
3029                 unpack_unreachable_expiration = 0;
3030
3031         /*
3032          * "soft" reasons not to use bitmaps - for on-disk repack by default we want
3033          *
3034          * - to produce good pack (with bitmap index not-yet-packed objects are
3035          *   packed in suboptimal order).
3036          *
3037          * - to use more robust pack-generation codepath (avoiding possible
3038          *   bugs in bitmap code and possible bitmap index corruption).
3039          */
3040         if (!pack_to_stdout)
3041                 use_bitmap_index_default = 0;
3042
3043         if (use_bitmap_index < 0)
3044                 use_bitmap_index = use_bitmap_index_default;
3045
3046         /* "hard" reasons not to use bitmaps; these just won't work at all */
3047         if (!use_internal_rev_list || (!pack_to_stdout && write_bitmap_index) || is_repository_shallow())
3048                 use_bitmap_index = 0;
3049
3050         if (pack_to_stdout || !rev_list_all)
3051                 write_bitmap_index = 0;
3052
3053         if (progress && all_progress_implied)
3054                 progress = 2;
3055
3056         prepare_packed_git();
3057         if (ignore_packed_keep) {
3058                 struct packed_git *p;
3059                 for (p = packed_git; p; p = p->next)
3060                         if (p->pack_local && p->pack_keep)
3061                                 break;
3062                 if (!p) /* no keep-able packs found */
3063                         ignore_packed_keep = 0;
3064         }
3065         if (local) {
3066                 /*
3067                  * unlike ignore_packed_keep above, we do not want to
3068                  * unset "local" based on looking at packs, as it
3069                  * also covers non-local objects
3070                  */
3071                 struct packed_git *p;
3072                 for (p = packed_git; p; p = p->next) {
3073                         if (!p->pack_local) {
3074                                 have_non_local_packs = 1;
3075                                 break;
3076                         }
3077                 }
3078         }
3079
3080         if (progress)
3081                 progress_state = start_progress(_("Counting objects"), 0);
3082         if (!use_internal_rev_list)
3083                 read_object_list_from_stdin();
3084         else {
3085                 get_object_list(rp.argc, rp.argv);
3086                 argv_array_clear(&rp);
3087         }
3088         cleanup_preferred_base();
3089         if (include_tag && nr_result)
3090                 for_each_ref(add_ref_tag, NULL);
3091         stop_progress(&progress_state);
3092
3093         if (non_empty && !nr_result)
3094                 return 0;
3095         if (nr_result)
3096                 prepare_pack(window, depth);
3097         write_pack_file();
3098         if (progress)
3099                 fprintf(stderr, "Total %"PRIu32" (delta %"PRIu32"),"
3100                         " reused %"PRIu32" (delta %"PRIu32")\n",
3101                         written, written_delta, reused, reused_delta);
3102         return 0;
3103 }