pack-objects.c

   1 #include "cache.h"
   2 #include "object.h"
   3 #include "delta.h"
   4 #include "pack.h"
   5 #include "csum-file.h"
   6 #include <sys/time.h>
   7
   8 static const char pack_usage[] = "git-pack-objects [-q] [--no-reuse-delta] [--non-empty] [--local] [--incremental] [--window=N] [--depth=N] {--stdout | base-name} < object-list";
   9
  10 struct object_entry {
  11         unsigned char sha1[20];
  12         unsigned long size;     /* uncompressed size */
  13         unsigned long offset;   /* offset into the final pack file;
  14                                  * nonzero if already written.
  15                                  */
  16         unsigned int depth;     /* delta depth */
  17         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  18         unsigned int hash;      /* name hint hash */
  19         enum object_type type;
  20         enum object_type in_pack_type;  /* could be delta */
  21         unsigned long delta_size;       /* delta data size (uncompressed) */
  22         struct object_entry *delta;     /* delta base object */
  23         struct packed_git *in_pack;     /* already in pack */
  24         unsigned int in_pack_offset;
  25         struct object_entry *delta_child; /* delitified objects who bases me */
  26         struct object_entry *delta_sibling; /* other deltified objects who
  27                                              * uses the same base as me
  28                                              */
  29 };
  30
  31 /*
  32  * Objects we are going to pack are colected in objects array (dynamically
  33  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  34  * in the order we see -- typically rev-list --objects order that gives us
  35  * nice "minimum seek" order.
  36  *
  37  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  38  * elements in the objects array.  The former is used to build the pack
  39  * index (lists object names in the ascending order to help offset lookup),
  40  * and the latter is used to group similar things together by try_delta()
  41  * heuristics.
  42  */
  43
  44 static unsigned char object_list_sha1[20];
  45 static int non_empty = 0;
  46 static int no_reuse_delta = 0;
  47 static int local = 0;
  48 static int incremental = 0;
  49 static struct object_entry **sorted_by_sha, **sorted_by_type;
  50 static struct object_entry *objects = NULL;
  51 static int nr_objects = 0, nr_alloc = 0;
  52 static const char *base_name;
  53 static unsigned char pack_file_sha1[20];
  54 static int progress = 1;
  55
  56 /*
  57  * The object names in objects array are hashed with this hashtable,
  58  * to help looking up the entry by object name.  Binary search from
  59  * sorted_by_sha is also possible but this was easier to code and faster.
  60  * This hashtable is built after all the objects are seen.
  61  */
  62 static int *object_ix = NULL;
  63 static int object_ix_hashsz = 0;
  64
  65 /*
  66  * Pack index for existing packs give us easy access to the offsets into
  67  * corresponding pack file where each object's data starts, but the entries
  68  * do not store the size of the compressed representation (uncompressed
  69  * size is easily available by examining the pack entry header).  We build
  70  * a hashtable of existing packs (pack_revindex), and keep reverse index
  71  * here -- pack index file is sorted by object name mapping to offset; this
  72  * pack_revindex[].revindex array is an ordered list of offsets, so if you
  73  * know the offset of an object, next offset is where its packed
  74  * representation ends.
  75  */
  76 struct pack_revindex {
  77         struct packed_git *p;
  78         unsigned long *revindex;
  79 } *pack_revindex = NULL;
  80 static int pack_revindex_hashsz = 0;
  81
  82 /*
  83  * stats
  84  */
  85 static int written = 0;
  86 static int written_delta = 0;
  87 static int reused = 0;
  88 static int reused_delta = 0;
  89
  90 static int pack_revindex_ix(struct packed_git *p)
  91 {
  92         unsigned int ui = (unsigned int) p;
  93         int i;
  94
  95         ui = ui ^ (ui >> 16); /* defeat structure alignment */
  96         i = (int)(ui % pack_revindex_hashsz);
  97         while (pack_revindex[i].p) {
  98                 if (pack_revindex[i].p == p)
  99                         return i;
 100                 if (++i == pack_revindex_hashsz)
 101                         i = 0;
 102         }
 103         return -1 - i;
 104 }
 105
 106 static void prepare_pack_ix(void)
 107 {
 108         int num;
 109         struct packed_git *p;
 110         for (num = 0, p = packed_git; p; p = p->next)
 111                 num++;
 112         if (!num)
 113                 return;
 114         pack_revindex_hashsz = num * 11;
 115         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 116         for (p = packed_git; p; p = p->next) {
 117                 num = pack_revindex_ix(p);
 118                 num = - 1 - num;
 119                 pack_revindex[num].p = p;
 120         }
 121         /* revindex elements are lazily initialized */
 122 }
 123
 124 static int cmp_offset(const void *a_, const void *b_)
 125 {
 126         unsigned long a = *(unsigned long *) a_;
 127         unsigned long b = *(unsigned long *) b_;
 128         if (a < b)
 129                 return -1;
 130         else if (a == b)
 131                 return 0;
 132         else
 133                 return 1;
 134 }
 135
 136 /*
 137  * Ordered list of offsets of objects in the pack.
 138  */
 139 static void prepare_pack_revindex(struct pack_revindex *rix)
 140 {
 141         struct packed_git *p = rix->p;
 142         int num_ent = num_packed_objects(p);
 143         int i;
 144         void *index = p->index_base + 256;
 145
 146         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 147         for (i = 0; i < num_ent; i++) {
 148                 long hl = *((long *)(index + 24 * i));
 149                 rix->revindex[i] = ntohl(hl);
 150         }
 151         /* This knows the pack format -- the 20-byte trailer
 152          * follows immediately after the last object data.
 153          */
 154         rix->revindex[num_ent] = p->pack_size - 20;
 155         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 156 }
 157
 158 static unsigned long find_packed_object_size(struct packed_git *p,
 159                                              unsigned long ofs)
 160 {
 161         int num;
 162         int lo, hi;
 163         struct pack_revindex *rix;
 164         unsigned long *revindex;
 165         num = pack_revindex_ix(p);
 166         if (num < 0)
 167                 die("internal error: pack revindex uninitialized");
 168         rix = &pack_revindex[num];
 169         if (!rix->revindex)
 170                 prepare_pack_revindex(rix);
 171         revindex = rix->revindex;
 172         lo = 0;
 173         hi = num_packed_objects(p) + 1;
 174         do {
 175                 int mi = (lo + hi) / 2;
 176                 if (revindex[mi] == ofs) {
 177                         return revindex[mi+1] - ofs;
 178                 }
 179                 else if (ofs < revindex[mi])
 180                         hi = mi;
 181                 else
 182                         lo = mi + 1;
 183         } while (lo < hi);
 184         die("internal error: pack revindex corrupt");
 185 }
 186
 187 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 188 {
 189         unsigned long othersize, delta_size;
 190         char type[10];
 191         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 192         void *delta_buf;
 193
 194         if (!otherbuf)
 195                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 196         delta_buf = diff_delta(otherbuf, othersize,
 197                                buf, size, &delta_size, 0);
 198         if (!delta_buf || delta_size != entry->delta_size)
 199                 die("delta size changed");
 200         free(buf);
 201         free(otherbuf);
 202         return delta_buf;
 203 }
 204
 205 /*
 206  * The per-object header is a pretty dense thing, which is
 207  *  - first byte: low four bits are "size", then three bits of "type",
 208  *    and the high bit is "size continues".
 209  *  - each byte afterwards: low seven bits are size continuation,
 210  *    with the high bit being "size continues"
 211  */
 212 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 213 {
 214         int n = 1;
 215         unsigned char c;
 216
 217         if (type < OBJ_COMMIT || type > OBJ_DELTA)
 218                 die("bad type %d", type);
 219
 220         c = (type << 4) | (size & 15);
 221         size >>= 4;
 222         while (size) {
 223                 *hdr++ = c | 0x80;
 224                 c = size & 0x7f;
 225                 size >>= 7;
 226                 n++;
 227         }
 228         *hdr = c;
 229         return n;
 230 }
 231
 232 static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
 233 {
 234         unsigned long size;
 235         char type[10];
 236         void *buf;
 237         unsigned char header[10];
 238         unsigned hdrlen, datalen;
 239         enum object_type obj_type;
 240         int to_reuse = 0;
 241
 242         obj_type = entry->type;
 243         if (! entry->in_pack)
 244                 to_reuse = 0;   /* can't reuse what we don't have */
 245         else if (obj_type == OBJ_DELTA)
 246                 to_reuse = 1;   /* check_object() decided it for us */
 247         else if (obj_type != entry->in_pack_type)
 248                 to_reuse = 0;   /* pack has delta which is unusable */
 249         else if (entry->delta)
 250                 to_reuse = 0;   /* we want to pack afresh */
 251         else
 252                 to_reuse = 1;   /* we have it in-pack undeltified,
 253                                  * and we do not need to deltify it.
 254                                  */
 255
 256         if (! to_reuse) {
 257                 buf = read_sha1_file(entry->sha1, type, &size);
 258                 if (!buf)
 259                         die("unable to read %s", sha1_to_hex(entry->sha1));
 260                 if (size != entry->size)
 261                         die("object %s size inconsistency (%lu vs %lu)",
 262                             sha1_to_hex(entry->sha1), size, entry->size);
 263                 if (entry->delta) {
 264                         buf = delta_against(buf, size, entry);
 265                         size = entry->delta_size;
 266                         obj_type = OBJ_DELTA;
 267                 }
 268                 /*
 269                  * The object header is a byte of 'type' followed by zero or
 270                  * more bytes of length.  For deltas, the 20 bytes of delta
 271                  * sha1 follows that.
 272                  */
 273                 hdrlen = encode_header(obj_type, size, header);
 274                 sha1write(f, header, hdrlen);
 275
 276                 if (entry->delta) {
 277                         sha1write(f, entry->delta, 20);
 278                         hdrlen += 20;
 279                 }
 280                 datalen = sha1write_compressed(f, buf, size);
 281                 free(buf);
 282         }
 283         else {
 284                 struct packed_git *p = entry->in_pack;
 285                 use_packed_git(p);
 286
 287                 datalen = find_packed_object_size(p, entry->in_pack_offset);
 288                 buf = p->pack_base + entry->in_pack_offset;
 289                 sha1write(f, buf, datalen);
 290                 unuse_packed_git(p);
 291                 hdrlen = 0; /* not really */
 292                 if (obj_type == OBJ_DELTA)
 293                         reused_delta++;
 294                 reused++;
 295         }
 296         if (obj_type == OBJ_DELTA)
 297                 written_delta++;
 298         written++;
 299         return hdrlen + datalen;
 300 }
 301
 302 static unsigned long write_one(struct sha1file *f,
 303                                struct object_entry *e,
 304                                unsigned long offset)
 305 {
 306         if (e->offset)
 307                 /* offset starts from header size and cannot be zero
 308                  * if it is written already.
 309                  */
 310                 return offset;
 311         e->offset = offset;
 312         offset += write_object(f, e);
 313         /* if we are deltified, write out its base object. */
 314         if (e->delta)
 315                 offset = write_one(f, e->delta, offset);
 316         return offset;
 317 }
 318
 319 static void write_pack_file(void)
 320 {
 321         int i;
 322         struct sha1file *f;
 323         unsigned long offset;
 324         struct pack_header hdr;
 325
 326         if (!base_name)
 327                 f = sha1fd(1, "<stdout>");
 328         else
 329                 f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "pack");
 330         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 331         hdr.hdr_version = htonl(PACK_VERSION);
 332         hdr.hdr_entries = htonl(nr_objects);
 333         sha1write(f, &hdr, sizeof(hdr));
 334         offset = sizeof(hdr);
 335         for (i = 0; i < nr_objects; i++)
 336                 offset = write_one(f, objects + i, offset);
 337
 338         sha1close(f, pack_file_sha1, 1);
 339 }
 340
 341 static void write_index_file(void)
 342 {
 343         int i;
 344         struct sha1file *f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "idx");
 345         struct object_entry **list = sorted_by_sha;
 346         struct object_entry **last = list + nr_objects;
 347         unsigned int array[256];
 348
 349         /*
 350          * Write the first-level table (the list is sorted,
 351          * but we use a 256-entry lookup to be able to avoid
 352          * having to do eight extra binary search iterations).
 353          */
 354         for (i = 0; i < 256; i++) {
 355                 struct object_entry **next = list;
 356                 while (next < last) {
 357                         struct object_entry *entry = *next;
 358                         if (entry->sha1[0] != i)
 359                                 break;
 360                         next++;
 361                 }
 362                 array[i] = htonl(next - sorted_by_sha);
 363                 list = next;
 364         }
 365         sha1write(f, array, 256 * sizeof(int));
 366
 367         /*
 368          * Write the actual SHA1 entries..
 369          */
 370         list = sorted_by_sha;
 371         for (i = 0; i < nr_objects; i++) {
 372                 struct object_entry *entry = *list++;
 373                 unsigned int offset = htonl(entry->offset);
 374                 sha1write(f, &offset, 4);
 375                 sha1write(f, entry->sha1, 20);
 376         }
 377         sha1write(f, pack_file_sha1, 20);
 378         sha1close(f, NULL, 1);
 379 }
 380
 381 static int add_object_entry(unsigned char *sha1, unsigned int hash)
 382 {
 383         unsigned int idx = nr_objects;
 384         struct object_entry *entry;
 385         struct packed_git *p;
 386         unsigned int found_offset = 0;
 387         struct packed_git *found_pack = NULL;
 388
 389         for (p = packed_git; p; p = p->next) {
 390                 struct pack_entry e;
 391                 if (find_pack_entry_one(sha1, &e, p)) {
 392                         if (incremental)
 393                                 return 0;
 394                         if (local && !p->pack_local)
 395                                 return 0;
 396                         if (!found_pack) {
 397                                 found_offset = e.offset;
 398                                 found_pack = e.p;
 399                         }
 400                 }
 401         }
 402
 403         if (idx >= nr_alloc) {
 404                 unsigned int needed = (idx + 1024) * 3 / 2;
 405                 objects = xrealloc(objects, needed * sizeof(*entry));
 406                 nr_alloc = needed;
 407         }
 408         entry = objects + idx;
 409         memset(entry, 0, sizeof(*entry));
 410         memcpy(entry->sha1, sha1, 20);
 411         entry->hash = hash;
 412         if (found_pack) {
 413                 entry->in_pack = found_pack;
 414                 entry->in_pack_offset = found_offset;
 415         }
 416         nr_objects = idx+1;
 417         return 1;
 418 }
 419
 420 static int locate_object_entry_hash(unsigned char *sha1)
 421 {
 422         int i;
 423         unsigned int ui;
 424         memcpy(&ui, sha1, sizeof(unsigned int));
 425         i = ui % object_ix_hashsz;
 426         while (0 < object_ix[i]) {
 427                 if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
 428                         return i;
 429                 if (++i == object_ix_hashsz)
 430                         i = 0;
 431         }
 432         return -1 - i;
 433 }
 434
 435 static struct object_entry *locate_object_entry(unsigned char *sha1)
 436 {
 437         int i = locate_object_entry_hash(sha1);
 438         if (0 <= i)
 439                 return &objects[object_ix[i]-1];
 440         return NULL;
 441 }
 442
 443 static void check_object(struct object_entry *entry)
 444 {
 445         char type[20];
 446
 447         if (entry->in_pack) {
 448                 unsigned char base[20];
 449                 unsigned long size;
 450                 struct object_entry *base_entry;
 451
 452                 /* We want in_pack_type even if we do not reuse delta.
 453                  * There is no point not reusing non-delta representations.
 454                  */
 455                 check_reuse_pack_delta(entry->in_pack,
 456                                        entry->in_pack_offset,
 457                                        base, &size,
 458                                        &entry->in_pack_type);
 459
 460                 /* Check if it is delta, and the base is also an object
 461                  * we are going to pack.  If so we will reuse the existing
 462                  * delta.
 463                  */
 464                 if (!no_reuse_delta &&
 465                     entry->in_pack_type == OBJ_DELTA &&
 466                     (base_entry = locate_object_entry(base))) {
 467
 468                         /* Depth value does not matter - find_deltas()
 469                          * will never consider reused delta as the
 470                          * base object to deltify other objects
 471                          * against, in order to avoid circular deltas.
 472                          */
 473
 474                         /* uncompressed size of the delta data */
 475                         entry->size = entry->delta_size = size;
 476                         entry->delta = base_entry;
 477                         entry->type = OBJ_DELTA;
 478
 479                         entry->delta_sibling = base_entry->delta_child;
 480                         base_entry->delta_child = entry;
 481
 482                         return;
 483                 }
 484                 /* Otherwise we would do the usual */
 485         }
 486
 487         if (sha1_object_info(entry->sha1, type, &entry->size))
 488                 die("unable to get type of object %s",
 489                     sha1_to_hex(entry->sha1));
 490
 491         if (!strcmp(type, "commit")) {
 492                 entry->type = OBJ_COMMIT;
 493         } else if (!strcmp(type, "tree")) {
 494                 entry->type = OBJ_TREE;
 495         } else if (!strcmp(type, "blob")) {
 496                 entry->type = OBJ_BLOB;
 497         } else if (!strcmp(type, "tag")) {
 498                 entry->type = OBJ_TAG;
 499         } else
 500                 die("unable to pack object %s of type %s",
 501                     sha1_to_hex(entry->sha1), type);
 502 }
 503
 504 static void hash_objects(void)
 505 {
 506         int i;
 507         struct object_entry *oe;
 508
 509         object_ix_hashsz = nr_objects * 2;
 510         object_ix = xcalloc(sizeof(int), object_ix_hashsz);
 511         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 512                 int ix = locate_object_entry_hash(oe->sha1);
 513                 if (0 <= ix) {
 514                         error("the same object '%s' added twice",
 515                               sha1_to_hex(oe->sha1));
 516                         continue;
 517                 }
 518                 ix = -1 - ix;
 519                 object_ix[ix] = i + 1;
 520         }
 521 }
 522
 523 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 524 {
 525         struct object_entry *child = me->delta_child;
 526         unsigned int m = n;
 527         while (child) {
 528                 unsigned int c = check_delta_limit(child, n + 1);
 529                 if (m < c)
 530                         m = c;
 531                 child = child->delta_sibling;
 532         }
 533         return m;
 534 }
 535
 536 static void get_object_details(void)
 537 {
 538         int i;
 539         struct object_entry *entry;
 540
 541         hash_objects();
 542         prepare_pack_ix();
 543         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 544                 check_object(entry);
 545         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 546                 if (!entry->delta && entry->delta_child)
 547                         entry->delta_limit =
 548                                 check_delta_limit(entry, 1);
 549 }
 550
 551 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 552
 553 static entry_sort_t current_sort;
 554
 555 static int sort_comparator(const void *_a, const void *_b)
 556 {
 557         struct object_entry *a = *(struct object_entry **)_a;
 558         struct object_entry *b = *(struct object_entry **)_b;
 559         return current_sort(a,b);
 560 }
 561
 562 static struct object_entry **create_sorted_list(entry_sort_t sort)
 563 {
 564         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 565         int i;
 566
 567         for (i = 0; i < nr_objects; i++)
 568                 list[i] = objects + i;
 569         current_sort = sort;
 570         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 571         return list;
 572 }
 573
 574 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 575 {
 576         return memcmp(a->sha1, b->sha1, 20);
 577 }
 578
 579 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 580 {
 581         if (a->type < b->type)
 582                 return -1;
 583         if (a->type > b->type)
 584                 return 1;
 585         if (a->hash < b->hash)
 586                 return -1;
 587         if (a->hash > b->hash)
 588                 return 1;
 589         if (a->size < b->size)
 590                 return -1;
 591         if (a->size > b->size)
 592                 return 1;
 593         return a < b ? -1 : (a > b);
 594 }
 595
 596 struct unpacked {
 597         struct object_entry *entry;
 598         void *data;
 599 };
 600
 601 /*
 602  * We search for deltas _backwards_ in a list sorted by type and
 603  * by size, so that we see progressively smaller and smaller files.
 604  * That's because we prefer deltas to be from the bigger file
 605  * to the smaller - deletes are potentially cheaper, but perhaps
 606  * more importantly, the bigger file is likely the more recent
 607  * one.
 608  */
 609 static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
 610 {
 611         struct object_entry *cur_entry = cur->entry;
 612         struct object_entry *old_entry = old->entry;
 613         unsigned long size, oldsize, delta_size, sizediff;
 614         long max_size;
 615         void *delta_buf;
 616
 617         /* Don't bother doing diffs between different types */
 618         if (cur_entry->type != old_entry->type)
 619                 return -1;
 620
 621         /* If the current object is at edge, take the depth the objects
 622          * that depend on the current object into account -- otherwise
 623          * they would become too deep.
 624          */
 625         if (cur_entry->delta_child) {
 626                 if (max_depth <= cur_entry->delta_limit)
 627                         return 0;
 628                 max_depth -= cur_entry->delta_limit;
 629         }
 630
 631         size = cur_entry->size;
 632         if (size < 50)
 633                 return -1;
 634         oldsize = old_entry->size;
 635         sizediff = oldsize > size ? oldsize - size : size - oldsize;
 636         if (sizediff > size / 8)
 637                 return -1;
 638         if (old_entry->depth >= max_depth)
 639                 return 0;
 640
 641         /*
 642          * NOTE!
 643          *
 644          * We always delta from the bigger to the smaller, since that's
 645          * more space-efficient (deletes don't have to say _what_ they
 646          * delete).
 647          */
 648         max_size = size / 2 - 20;
 649         if (cur_entry->delta)
 650                 max_size = cur_entry->delta_size-1;
 651         if (sizediff >= max_size)
 652                 return -1;
 653         delta_buf = diff_delta(old->data, oldsize,
 654                                cur->data, size, &delta_size, max_size);
 655         if (!delta_buf)
 656                 return 0;
 657         cur_entry->delta = old_entry;
 658         cur_entry->delta_size = delta_size;
 659         cur_entry->depth = old_entry->depth + 1;
 660         free(delta_buf);
 661         return 0;
 662 }
 663
 664 static void find_deltas(struct object_entry **list, int window, int depth)
 665 {
 666         int i, idx;
 667         unsigned int array_size = window * sizeof(struct unpacked);
 668         struct unpacked *array = xmalloc(array_size);
 669         int eye_candy;
 670
 671         memset(array, 0, array_size);
 672         i = nr_objects;
 673         idx = 0;
 674         eye_candy = i - (nr_objects / 20);
 675
 676         while (--i >= 0) {
 677                 struct object_entry *entry = list[i];
 678                 struct unpacked *n = array + idx;
 679                 unsigned long size;
 680                 char type[10];
 681                 int j;
 682
 683                 if (progress && i <= eye_candy) {
 684                         eye_candy -= nr_objects / 20;
 685                         fputc('.', stderr);
 686                 }
 687
 688                 if (entry->delta)
 689                         /* This happens if we decided to reuse existing
 690                          * delta from a pack.  "!no_reuse_delta &&" is implied.
 691                          */
 692                         continue;
 693
 694                 free(n->data);
 695                 n->entry = entry;
 696                 n->data = read_sha1_file(entry->sha1, type, &size);
 697                 if (size != entry->size)
 698                         die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
 699
 700                 j = window;
 701                 while (--j > 0) {
 702                         unsigned int other_idx = idx + j;
 703                         struct unpacked *m;
 704                         if (other_idx >= window)
 705                                 other_idx -= window;
 706                         m = array + other_idx;
 707                         if (!m->entry)
 708                                 break;
 709                         if (try_delta(n, m, depth) < 0)
 710                                 break;
 711                 }
 712                 idx++;
 713                 if (idx >= window)
 714                         idx = 0;
 715         }
 716
 717         for (i = 0; i < window; ++i)
 718                 free(array[i].data);
 719         free(array);
 720 }
 721
 722 static void prepare_pack(int window, int depth)
 723 {
 724         if (progress)
 725                 fprintf(stderr, "Packing %d objects", nr_objects);
 726         get_object_details();
 727         if (progress)
 728                 fputc('.', stderr);
 729
 730         sorted_by_type = create_sorted_list(type_size_sort);
 731         if (window && depth)
 732                 find_deltas(sorted_by_type, window+1, depth);
 733         if (progress)
 734                 fputc('\n', stderr);
 735         write_pack_file();
 736 }
 737
 738 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
 739 {
 740         static const char cache[] = "pack-cache/pack-%s.%s";
 741         char *cached_pack, *cached_idx;
 742         int ifd, ofd, ifd_ix = -1;
 743
 744         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
 745         ifd = open(cached_pack, O_RDONLY);
 746         if (ifd < 0)
 747                 return 0;
 748
 749         if (!pack_to_stdout) {
 750                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
 751                 ifd_ix = open(cached_idx, O_RDONLY);
 752                 if (ifd_ix < 0) {
 753                         close(ifd);
 754                         return 0;
 755                 }
 756         }
 757
 758         if (progress)
 759                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
 760                         sha1_to_hex(sha1));
 761
 762         if (pack_to_stdout) {
 763                 if (copy_fd(ifd, 1))
 764                         exit(1);
 765                 close(ifd);
 766         }
 767         else {
 768                 char name[PATH_MAX];
 769                 snprintf(name, sizeof(name),
 770                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
 771                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
 772                 if (ofd < 0)
 773                         die("unable to open %s (%s)", name, strerror(errno));
 774                 if (copy_fd(ifd, ofd))
 775                         exit(1);
 776                 close(ifd);
 777
 778                 snprintf(name, sizeof(name),
 779                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
 780                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
 781                 if (ofd < 0)
 782                         die("unable to open %s (%s)", name, strerror(errno));
 783                 if (copy_fd(ifd_ix, ofd))
 784                         exit(1);
 785                 close(ifd_ix);
 786                 puts(sha1_to_hex(sha1));
 787         }
 788
 789         return 1;
 790 }
 791
 792 int main(int argc, char **argv)
 793 {
 794         SHA_CTX ctx;
 795         char line[PATH_MAX + 20];
 796         int window = 10, depth = 10, pack_to_stdout = 0;
 797         struct object_entry **list;
 798         int i;
 799         struct timeval prev_tv;
 800         int eye_candy = 0;
 801         int eye_candy_incr = 500;
 802
 803
 804         setup_git_directory();
 805
 806         for (i = 1; i < argc; i++) {
 807                 const char *arg = argv[i];
 808
 809                 if (*arg == '-') {
 810                         if (!strcmp("--non-empty", arg)) {
 811                                 non_empty = 1;
 812                                 continue;
 813                         }
 814                         if (!strcmp("--local", arg)) {
 815                                 local = 1;
 816                                 continue;
 817                         }
 818                         if (!strcmp("--incremental", arg)) {
 819                                 incremental = 1;
 820                                 continue;
 821                         }
 822                         if (!strncmp("--window=", arg, 9)) {
 823                                 char *end;
 824                                 window = strtoul(arg+9, &end, 0);
 825                                 if (!arg[9] || *end)
 826                                         usage(pack_usage);
 827                                 continue;
 828                         }
 829                         if (!strncmp("--depth=", arg, 8)) {
 830                                 char *end;
 831                                 depth = strtoul(arg+8, &end, 0);
 832                                 if (!arg[8] || *end)
 833                                         usage(pack_usage);
 834                                 continue;
 835                         }
 836                         if (!strcmp("-q", arg)) {
 837                                 progress = 0;
 838                                 continue;
 839                         }
 840                         if (!strcmp("--no-reuse-delta", arg)) {
 841                                 no_reuse_delta = 1;
 842                                 continue;
 843                         }
 844                         if (!strcmp("--stdout", arg)) {
 845                                 pack_to_stdout = 1;
 846                                 continue;
 847                         }
 848                         usage(pack_usage);
 849                 }
 850                 if (base_name)
 851                         usage(pack_usage);
 852                 base_name = arg;
 853         }
 854
 855         if (pack_to_stdout != !base_name)
 856                 usage(pack_usage);
 857
 858         prepare_packed_git();
 859         if (progress) {
 860                 fprintf(stderr, "Generating pack...\n");
 861                 gettimeofday(&prev_tv, NULL);
 862         }
 863         while (fgets(line, sizeof(line), stdin) != NULL) {
 864                 unsigned int hash;
 865                 char *p;
 866                 unsigned char sha1[20];
 867
 868                 if (progress && (eye_candy <= nr_objects)) {
 869                         fprintf(stderr, "Counting objects...%d\r", nr_objects);
 870                         if (eye_candy && (50 <= eye_candy_incr)) {
 871                                 struct timeval tv;
 872                                 int time_diff;
 873                                 gettimeofday(&tv, NULL);
 874                                 time_diff = (tv.tv_sec - prev_tv.tv_sec);
 875                                 time_diff <<= 10;
 876                                 time_diff += (tv.tv_usec - prev_tv.tv_usec);
 877                                 if ((1 << 9) < time_diff)
 878                                         eye_candy_incr += 50;
 879                                 else if (50 < eye_candy_incr)
 880                                         eye_candy_incr -= 50;
 881                         }
 882                         eye_candy += eye_candy_incr;
 883                 }
 884                 if (get_sha1_hex(line, sha1))
 885                         die("expected sha1, got garbage:\n %s", line);
 886                 hash = 0;
 887                 p = line+40;
 888                 while (*p) {
 889                         unsigned char c = *p++;
 890                         if (isspace(c))
 891                                 continue;
 892                         hash = hash * 11 + c;
 893                 }
 894                 add_object_entry(sha1, hash);
 895         }
 896         if (progress)
 897                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
 898         if (non_empty && !nr_objects)
 899                 return 0;
 900
 901         sorted_by_sha = create_sorted_list(sha1_sort);
 902         SHA1_Init(&ctx);
 903         list = sorted_by_sha;
 904         for (i = 0; i < nr_objects; i++) {
 905                 struct object_entry *entry = *list++;
 906                 SHA1_Update(&ctx, entry->sha1, 20);
 907         }
 908         SHA1_Final(object_list_sha1, &ctx);
 909
 910         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
 911                 ;
 912         else {
 913                 prepare_pack(window, depth);
 914                 if (!pack_to_stdout) {
 915                         write_index_file();
 916                         puts(sha1_to_hex(object_list_sha1));
 917                 }
 918         }
 919         if (progress)
 920                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
 921                         nr_objects, written, written_delta, reused, reused_delta);
 922         return 0;
 923 }