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 #include <signal.h>
   8
   9 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";
  10
  11 struct object_entry {
  12         unsigned char sha1[20];
  13         unsigned long size;     /* uncompressed size */
  14         unsigned long offset;   /* offset into the final pack file;
  15                                  * nonzero if already written.
  16                                  */
  17         unsigned int depth;     /* delta depth */
  18         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  19         unsigned int hash;      /* name hint hash */
  20         enum object_type type;
  21         enum object_type in_pack_type;  /* could be delta */
  22         unsigned long delta_size;       /* delta data size (uncompressed) */
  23         struct object_entry *delta;     /* delta base object */
  24         struct packed_git *in_pack;     /* already in pack */
  25         unsigned int in_pack_offset;
  26         struct object_entry *delta_child; /* delitified objects who bases me */
  27         struct object_entry *delta_sibling; /* other deltified objects who
  28                                              * uses the same base as me
  29                                              */
  30 };
  31
  32 /*
  33  * Objects we are going to pack are colected in objects array (dynamically
  34  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  35  * in the order we see -- typically rev-list --objects order that gives us
  36  * nice "minimum seek" order.
  37  *
  38  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  39  * elements in the objects array.  The former is used to build the pack
  40  * index (lists object names in the ascending order to help offset lookup),
  41  * and the latter is used to group similar things together by try_delta()
  42  * heuristics.
  43  */
  44
  45 static unsigned char object_list_sha1[20];
  46 static int non_empty = 0;
  47 static int no_reuse_delta = 0;
  48 static int local = 0;
  49 static int incremental = 0;
  50 static struct object_entry **sorted_by_sha, **sorted_by_type;
  51 static struct object_entry *objects = NULL;
  52 static int nr_objects = 0, nr_alloc = 0;
  53 static const char *base_name;
  54 static unsigned char pack_file_sha1[20];
  55 static int progress = 1;
  56 static volatile int progress_update = 0;
  57
  58 /*
  59  * The object names in objects array are hashed with this hashtable,
  60  * to help looking up the entry by object name.  Binary search from
  61  * sorted_by_sha is also possible but this was easier to code and faster.
  62  * This hashtable is built after all the objects are seen.
  63  */
  64 static int *object_ix = NULL;
  65 static int object_ix_hashsz = 0;
  66
  67 /*
  68  * Pack index for existing packs give us easy access to the offsets into
  69  * corresponding pack file where each object's data starts, but the entries
  70  * do not store the size of the compressed representation (uncompressed
  71  * size is easily available by examining the pack entry header).  We build
  72  * a hashtable of existing packs (pack_revindex), and keep reverse index
  73  * here -- pack index file is sorted by object name mapping to offset; this
  74  * pack_revindex[].revindex array is an ordered list of offsets, so if you
  75  * know the offset of an object, next offset is where its packed
  76  * representation ends.
  77  */
  78 struct pack_revindex {
  79         struct packed_git *p;
  80         unsigned long *revindex;
  81 } *pack_revindex = NULL;
  82 static int pack_revindex_hashsz = 0;
  83
  84 /*
  85  * stats
  86  */
  87 static int written = 0;
  88 static int written_delta = 0;
  89 static int reused = 0;
  90 static int reused_delta = 0;
  91
  92 static int pack_revindex_ix(struct packed_git *p)
  93 {
  94         unsigned int ui = (unsigned int) p;
  95         int i;
  96
  97         ui = ui ^ (ui >> 16); /* defeat structure alignment */
  98         i = (int)(ui % pack_revindex_hashsz);
  99         while (pack_revindex[i].p) {
 100                 if (pack_revindex[i].p == p)
 101                         return i;
 102                 if (++i == pack_revindex_hashsz)
 103                         i = 0;
 104         }
 105         return -1 - i;
 106 }
 107
 108 static void prepare_pack_ix(void)
 109 {
 110         int num;
 111         struct packed_git *p;
 112         for (num = 0, p = packed_git; p; p = p->next)
 113                 num++;
 114         if (!num)
 115                 return;
 116         pack_revindex_hashsz = num * 11;
 117         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 118         for (p = packed_git; p; p = p->next) {
 119                 num = pack_revindex_ix(p);
 120                 num = - 1 - num;
 121                 pack_revindex[num].p = p;
 122         }
 123         /* revindex elements are lazily initialized */
 124 }
 125
 126 static int cmp_offset(const void *a_, const void *b_)
 127 {
 128         unsigned long a = *(unsigned long *) a_;
 129         unsigned long b = *(unsigned long *) b_;
 130         if (a < b)
 131                 return -1;
 132         else if (a == b)
 133                 return 0;
 134         else
 135                 return 1;
 136 }
 137
 138 /*
 139  * Ordered list of offsets of objects in the pack.
 140  */
 141 static void prepare_pack_revindex(struct pack_revindex *rix)
 142 {
 143         struct packed_git *p = rix->p;
 144         int num_ent = num_packed_objects(p);
 145         int i;
 146         void *index = p->index_base + 256;
 147
 148         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 149         for (i = 0; i < num_ent; i++) {
 150                 long hl = *((long *)(index + 24 * i));
 151                 rix->revindex[i] = ntohl(hl);
 152         }
 153         /* This knows the pack format -- the 20-byte trailer
 154          * follows immediately after the last object data.
 155          */
 156         rix->revindex[num_ent] = p->pack_size - 20;
 157         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 158 }
 159
 160 static unsigned long find_packed_object_size(struct packed_git *p,
 161                                              unsigned long ofs)
 162 {
 163         int num;
 164         int lo, hi;
 165         struct pack_revindex *rix;
 166         unsigned long *revindex;
 167         num = pack_revindex_ix(p);
 168         if (num < 0)
 169                 die("internal error: pack revindex uninitialized");
 170         rix = &pack_revindex[num];
 171         if (!rix->revindex)
 172                 prepare_pack_revindex(rix);
 173         revindex = rix->revindex;
 174         lo = 0;
 175         hi = num_packed_objects(p) + 1;
 176         do {
 177                 int mi = (lo + hi) / 2;
 178                 if (revindex[mi] == ofs) {
 179                         return revindex[mi+1] - ofs;
 180                 }
 181                 else if (ofs < revindex[mi])
 182                         hi = mi;
 183                 else
 184                         lo = mi + 1;
 185         } while (lo < hi);
 186         die("internal error: pack revindex corrupt");
 187 }
 188
 189 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 190 {
 191         unsigned long othersize, delta_size;
 192         char type[10];
 193         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 194         void *delta_buf;
 195
 196         if (!otherbuf)
 197                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 198         delta_buf = diff_delta(otherbuf, othersize,
 199                                buf, size, &delta_size, 0);
 200         if (!delta_buf || delta_size != entry->delta_size)
 201                 die("delta size changed");
 202         free(buf);
 203         free(otherbuf);
 204         return delta_buf;
 205 }
 206
 207 /*
 208  * The per-object header is a pretty dense thing, which is
 209  *  - first byte: low four bits are "size", then three bits of "type",
 210  *    and the high bit is "size continues".
 211  *  - each byte afterwards: low seven bits are size continuation,
 212  *    with the high bit being "size continues"
 213  */
 214 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 215 {
 216         int n = 1;
 217         unsigned char c;
 218
 219         if (type < OBJ_COMMIT || type > OBJ_DELTA)
 220                 die("bad type %d", type);
 221
 222         c = (type << 4) | (size & 15);
 223         size >>= 4;
 224         while (size) {
 225                 *hdr++ = c | 0x80;
 226                 c = size & 0x7f;
 227                 size >>= 7;
 228                 n++;
 229         }
 230         *hdr = c;
 231         return n;
 232 }
 233
 234 static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
 235 {
 236         unsigned long size;
 237         char type[10];
 238         void *buf;
 239         unsigned char header[10];
 240         unsigned hdrlen, datalen;
 241         enum object_type obj_type;
 242         int to_reuse = 0;
 243
 244         obj_type = entry->type;
 245         if (! entry->in_pack)
 246                 to_reuse = 0;   /* can't reuse what we don't have */
 247         else if (obj_type == OBJ_DELTA)
 248                 to_reuse = 1;   /* check_object() decided it for us */
 249         else if (obj_type != entry->in_pack_type)
 250                 to_reuse = 0;   /* pack has delta which is unusable */
 251         else if (entry->delta)
 252                 to_reuse = 0;   /* we want to pack afresh */
 253         else
 254                 to_reuse = 1;   /* we have it in-pack undeltified,
 255                                  * and we do not need to deltify it.
 256                                  */
 257
 258         if (! to_reuse) {
 259                 buf = read_sha1_file(entry->sha1, type, &size);
 260                 if (!buf)
 261                         die("unable to read %s", sha1_to_hex(entry->sha1));
 262                 if (size != entry->size)
 263                         die("object %s size inconsistency (%lu vs %lu)",
 264                             sha1_to_hex(entry->sha1), size, entry->size);
 265                 if (entry->delta) {
 266                         buf = delta_against(buf, size, entry);
 267                         size = entry->delta_size;
 268                         obj_type = OBJ_DELTA;
 269                 }
 270                 /*
 271                  * The object header is a byte of 'type' followed by zero or
 272                  * more bytes of length.  For deltas, the 20 bytes of delta
 273                  * sha1 follows that.
 274                  */
 275                 hdrlen = encode_header(obj_type, size, header);
 276                 sha1write(f, header, hdrlen);
 277
 278                 if (entry->delta) {
 279                         sha1write(f, entry->delta, 20);
 280                         hdrlen += 20;
 281                 }
 282                 datalen = sha1write_compressed(f, buf, size);
 283                 free(buf);
 284         }
 285         else {
 286                 struct packed_git *p = entry->in_pack;
 287                 use_packed_git(p);
 288
 289                 datalen = find_packed_object_size(p, entry->in_pack_offset);
 290                 buf = p->pack_base + entry->in_pack_offset;
 291                 sha1write(f, buf, datalen);
 292                 unuse_packed_git(p);
 293                 hdrlen = 0; /* not really */
 294                 if (obj_type == OBJ_DELTA)
 295                         reused_delta++;
 296                 reused++;
 297         }
 298         if (obj_type == OBJ_DELTA)
 299                 written_delta++;
 300         written++;
 301         return hdrlen + datalen;
 302 }
 303
 304 static unsigned long write_one(struct sha1file *f,
 305                                struct object_entry *e,
 306                                unsigned long offset)
 307 {
 308         if (e->offset)
 309                 /* offset starts from header size and cannot be zero
 310                  * if it is written already.
 311                  */
 312                 return offset;
 313         e->offset = offset;
 314         offset += write_object(f, e);
 315         /* if we are deltified, write out its base object. */
 316         if (e->delta)
 317                 offset = write_one(f, e->delta, offset);
 318         return offset;
 319 }
 320
 321 static void write_pack_file(void)
 322 {
 323         int i;
 324         struct sha1file *f;
 325         unsigned long offset;
 326         struct pack_header hdr;
 327         unsigned last_percent = 999;
 328         int do_progress = 0;
 329
 330         if (!base_name)
 331                 f = sha1fd(1, "<stdout>");
 332         else {
 333                 f = sha1create("%s-%s.%s", base_name,
 334                                sha1_to_hex(object_list_sha1), "pack");
 335                 do_progress = progress;
 336         }
 337         if (do_progress)
 338                 fprintf(stderr, "Writing %d objects.\n", nr_objects);
 339
 340         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 341         hdr.hdr_version = htonl(PACK_VERSION);
 342         hdr.hdr_entries = htonl(nr_objects);
 343         sha1write(f, &hdr, sizeof(hdr));
 344         offset = sizeof(hdr);
 345         for (i = 0; i < nr_objects; i++) {
 346                 offset = write_one(f, objects + i, offset);
 347                 if (do_progress) {
 348                         unsigned percent = written * 100 / nr_objects;
 349                         if (progress_update || percent != last_percent) {
 350                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 351                                         percent, written, nr_objects);
 352                                 progress_update = 0;
 353                                 last_percent = percent;
 354                         }
 355                 }
 356         }
 357         if (do_progress)
 358                 fputc('\n', stderr);
 359
 360         sha1close(f, pack_file_sha1, 1);
 361 }
 362
 363 static void write_index_file(void)
 364 {
 365         int i;
 366         struct sha1file *f = sha1create("%s-%s.%s", base_name, sha1_to_hex(object_list_sha1), "idx");
 367         struct object_entry **list = sorted_by_sha;
 368         struct object_entry **last = list + nr_objects;
 369         unsigned int array[256];
 370
 371         /*
 372          * Write the first-level table (the list is sorted,
 373          * but we use a 256-entry lookup to be able to avoid
 374          * having to do eight extra binary search iterations).
 375          */
 376         for (i = 0; i < 256; i++) {
 377                 struct object_entry **next = list;
 378                 while (next < last) {
 379                         struct object_entry *entry = *next;
 380                         if (entry->sha1[0] != i)
 381                                 break;
 382                         next++;
 383                 }
 384                 array[i] = htonl(next - sorted_by_sha);
 385                 list = next;
 386         }
 387         sha1write(f, array, 256 * sizeof(int));
 388
 389         /*
 390          * Write the actual SHA1 entries..
 391          */
 392         list = sorted_by_sha;
 393         for (i = 0; i < nr_objects; i++) {
 394                 struct object_entry *entry = *list++;
 395                 unsigned int offset = htonl(entry->offset);
 396                 sha1write(f, &offset, 4);
 397                 sha1write(f, entry->sha1, 20);
 398         }
 399         sha1write(f, pack_file_sha1, 20);
 400         sha1close(f, NULL, 1);
 401 }
 402
 403 static int add_object_entry(unsigned char *sha1, unsigned int hash)
 404 {
 405         unsigned int idx = nr_objects;
 406         struct object_entry *entry;
 407         struct packed_git *p;
 408         unsigned int found_offset = 0;
 409         struct packed_git *found_pack = NULL;
 410
 411         for (p = packed_git; p; p = p->next) {
 412                 struct pack_entry e;
 413                 if (find_pack_entry_one(sha1, &e, p)) {
 414                         if (incremental)
 415                                 return 0;
 416                         if (local && !p->pack_local)
 417                                 return 0;
 418                         if (!found_pack) {
 419                                 found_offset = e.offset;
 420                                 found_pack = e.p;
 421                         }
 422                 }
 423         }
 424
 425         if (idx >= nr_alloc) {
 426                 unsigned int needed = (idx + 1024) * 3 / 2;
 427                 objects = xrealloc(objects, needed * sizeof(*entry));
 428                 nr_alloc = needed;
 429         }
 430         entry = objects + idx;
 431         memset(entry, 0, sizeof(*entry));
 432         memcpy(entry->sha1, sha1, 20);
 433         entry->hash = hash;
 434         if (found_pack) {
 435                 entry->in_pack = found_pack;
 436                 entry->in_pack_offset = found_offset;
 437         }
 438         nr_objects = idx+1;
 439         return 1;
 440 }
 441
 442 static int locate_object_entry_hash(unsigned char *sha1)
 443 {
 444         int i;
 445         unsigned int ui;
 446         memcpy(&ui, sha1, sizeof(unsigned int));
 447         i = ui % object_ix_hashsz;
 448         while (0 < object_ix[i]) {
 449                 if (!memcmp(sha1, objects[object_ix[i]-1].sha1, 20))
 450                         return i;
 451                 if (++i == object_ix_hashsz)
 452                         i = 0;
 453         }
 454         return -1 - i;
 455 }
 456
 457 static struct object_entry *locate_object_entry(unsigned char *sha1)
 458 {
 459         int i = locate_object_entry_hash(sha1);
 460         if (0 <= i)
 461                 return &objects[object_ix[i]-1];
 462         return NULL;
 463 }
 464
 465 static void check_object(struct object_entry *entry)
 466 {
 467         char type[20];
 468
 469         if (entry->in_pack) {
 470                 unsigned char base[20];
 471                 unsigned long size;
 472                 struct object_entry *base_entry;
 473
 474                 /* We want in_pack_type even if we do not reuse delta.
 475                  * There is no point not reusing non-delta representations.
 476                  */
 477                 check_reuse_pack_delta(entry->in_pack,
 478                                        entry->in_pack_offset,
 479                                        base, &size,
 480                                        &entry->in_pack_type);
 481
 482                 /* Check if it is delta, and the base is also an object
 483                  * we are going to pack.  If so we will reuse the existing
 484                  * delta.
 485                  */
 486                 if (!no_reuse_delta &&
 487                     entry->in_pack_type == OBJ_DELTA &&
 488                     (base_entry = locate_object_entry(base))) {
 489
 490                         /* Depth value does not matter - find_deltas()
 491                          * will never consider reused delta as the
 492                          * base object to deltify other objects
 493                          * against, in order to avoid circular deltas.
 494                          */
 495
 496                         /* uncompressed size of the delta data */
 497                         entry->size = entry->delta_size = size;
 498                         entry->delta = base_entry;
 499                         entry->type = OBJ_DELTA;
 500
 501                         entry->delta_sibling = base_entry->delta_child;
 502                         base_entry->delta_child = entry;
 503
 504                         return;
 505                 }
 506                 /* Otherwise we would do the usual */
 507         }
 508
 509         if (sha1_object_info(entry->sha1, type, &entry->size))
 510                 die("unable to get type of object %s",
 511                     sha1_to_hex(entry->sha1));
 512
 513         if (!strcmp(type, "commit")) {
 514                 entry->type = OBJ_COMMIT;
 515         } else if (!strcmp(type, "tree")) {
 516                 entry->type = OBJ_TREE;
 517         } else if (!strcmp(type, "blob")) {
 518                 entry->type = OBJ_BLOB;
 519         } else if (!strcmp(type, "tag")) {
 520                 entry->type = OBJ_TAG;
 521         } else
 522                 die("unable to pack object %s of type %s",
 523                     sha1_to_hex(entry->sha1), type);
 524 }
 525
 526 static void hash_objects(void)
 527 {
 528         int i;
 529         struct object_entry *oe;
 530
 531         object_ix_hashsz = nr_objects * 2;
 532         object_ix = xcalloc(sizeof(int), object_ix_hashsz);
 533         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 534                 int ix = locate_object_entry_hash(oe->sha1);
 535                 if (0 <= ix) {
 536                         error("the same object '%s' added twice",
 537                               sha1_to_hex(oe->sha1));
 538                         continue;
 539                 }
 540                 ix = -1 - ix;
 541                 object_ix[ix] = i + 1;
 542         }
 543 }
 544
 545 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 546 {
 547         struct object_entry *child = me->delta_child;
 548         unsigned int m = n;
 549         while (child) {
 550                 unsigned int c = check_delta_limit(child, n + 1);
 551                 if (m < c)
 552                         m = c;
 553                 child = child->delta_sibling;
 554         }
 555         return m;
 556 }
 557
 558 static void get_object_details(void)
 559 {
 560         int i;
 561         struct object_entry *entry;
 562
 563         hash_objects();
 564         prepare_pack_ix();
 565         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 566                 check_object(entry);
 567         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 568                 if (!entry->delta && entry->delta_child)
 569                         entry->delta_limit =
 570                                 check_delta_limit(entry, 1);
 571 }
 572
 573 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 574
 575 static entry_sort_t current_sort;
 576
 577 static int sort_comparator(const void *_a, const void *_b)
 578 {
 579         struct object_entry *a = *(struct object_entry **)_a;
 580         struct object_entry *b = *(struct object_entry **)_b;
 581         return current_sort(a,b);
 582 }
 583
 584 static struct object_entry **create_sorted_list(entry_sort_t sort)
 585 {
 586         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 587         int i;
 588
 589         for (i = 0; i < nr_objects; i++)
 590                 list[i] = objects + i;
 591         current_sort = sort;
 592         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 593         return list;
 594 }
 595
 596 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 597 {
 598         return memcmp(a->sha1, b->sha1, 20);
 599 }
 600
 601 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 602 {
 603         if (a->type < b->type)
 604                 return -1;
 605         if (a->type > b->type)
 606                 return 1;
 607         if (a->hash < b->hash)
 608                 return -1;
 609         if (a->hash > b->hash)
 610                 return 1;
 611         if (a->size < b->size)
 612                 return -1;
 613         if (a->size > b->size)
 614                 return 1;
 615         return a < b ? -1 : (a > b);
 616 }
 617
 618 struct unpacked {
 619         struct object_entry *entry;
 620         void *data;
 621 };
 622
 623 /*
 624  * We search for deltas _backwards_ in a list sorted by type and
 625  * by size, so that we see progressively smaller and smaller files.
 626  * That's because we prefer deltas to be from the bigger file
 627  * to the smaller - deletes are potentially cheaper, but perhaps
 628  * more importantly, the bigger file is likely the more recent
 629  * one.
 630  */
 631 static int try_delta(struct unpacked *cur, struct unpacked *old, unsigned max_depth)
 632 {
 633         struct object_entry *cur_entry = cur->entry;
 634         struct object_entry *old_entry = old->entry;
 635         unsigned long size, oldsize, delta_size, sizediff;
 636         long max_size;
 637         void *delta_buf;
 638
 639         /* Don't bother doing diffs between different types */
 640         if (cur_entry->type != old_entry->type)
 641                 return -1;
 642
 643         /* If the current object is at edge, take the depth the objects
 644          * that depend on the current object into account -- otherwise
 645          * they would become too deep.
 646          */
 647         if (cur_entry->delta_child) {
 648                 if (max_depth <= cur_entry->delta_limit)
 649                         return 0;
 650                 max_depth -= cur_entry->delta_limit;
 651         }
 652
 653         size = cur_entry->size;
 654         if (size < 50)
 655                 return -1;
 656         oldsize = old_entry->size;
 657         sizediff = oldsize > size ? oldsize - size : size - oldsize;
 658         if (sizediff > size / 8)
 659                 return -1;
 660         if (old_entry->depth >= max_depth)
 661                 return 0;
 662
 663         /*
 664          * NOTE!
 665          *
 666          * We always delta from the bigger to the smaller, since that's
 667          * more space-efficient (deletes don't have to say _what_ they
 668          * delete).
 669          */
 670         max_size = size / 2 - 20;
 671         if (cur_entry->delta)
 672                 max_size = cur_entry->delta_size-1;
 673         if (sizediff >= max_size)
 674                 return -1;
 675         delta_buf = diff_delta(old->data, oldsize,
 676                                cur->data, size, &delta_size, max_size);
 677         if (!delta_buf)
 678                 return 0;
 679         cur_entry->delta = old_entry;
 680         cur_entry->delta_size = delta_size;
 681         cur_entry->depth = old_entry->depth + 1;
 682         free(delta_buf);
 683         return 0;
 684 }
 685
 686 static void progress_interval(int signum)
 687 {
 688         signal(SIGALRM, progress_interval);
 689         progress_update = 1;
 690 }
 691
 692 static void find_deltas(struct object_entry **list, int window, int depth)
 693 {
 694         int i, idx;
 695         unsigned int array_size = window * sizeof(struct unpacked);
 696         struct unpacked *array = xmalloc(array_size);
 697         unsigned processed = 0;
 698         unsigned last_percent = 999;
 699
 700         memset(array, 0, array_size);
 701         i = nr_objects;
 702         idx = 0;
 703         if (progress)
 704                 fprintf(stderr, "Deltifying %d objects.\n", nr_objects);
 705
 706         while (--i >= 0) {
 707                 struct object_entry *entry = list[i];
 708                 struct unpacked *n = array + idx;
 709                 unsigned long size;
 710                 char type[10];
 711                 int j;
 712
 713                 processed++;
 714                 if (progress) {
 715                         unsigned percent = processed * 100 / nr_objects;
 716                         if (percent != last_percent || progress_update) {
 717                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 718                                         percent, processed, nr_objects);
 719                                 progress_update = 0;
 720                                 last_percent = percent;
 721                         }
 722                 }
 723
 724                 if (entry->delta)
 725                         /* This happens if we decided to reuse existing
 726                          * delta from a pack.  "!no_reuse_delta &&" is implied.
 727                          */
 728                         continue;
 729
 730                 free(n->data);
 731                 n->entry = entry;
 732                 n->data = read_sha1_file(entry->sha1, type, &size);
 733                 if (size != entry->size)
 734                         die("object %s inconsistent object length (%lu vs %lu)", sha1_to_hex(entry->sha1), size, entry->size);
 735
 736                 j = window;
 737                 while (--j > 0) {
 738                         unsigned int other_idx = idx + j;
 739                         struct unpacked *m;
 740                         if (other_idx >= window)
 741                                 other_idx -= window;
 742                         m = array + other_idx;
 743                         if (!m->entry)
 744                                 break;
 745                         if (try_delta(n, m, depth) < 0)
 746                                 break;
 747                 }
 748                 idx++;
 749                 if (idx >= window)
 750                         idx = 0;
 751         }
 752
 753         if (progress)
 754                 fputc('\n', stderr);
 755
 756         for (i = 0; i < window; ++i)
 757                 free(array[i].data);
 758         free(array);
 759 }
 760
 761 static void prepare_pack(int window, int depth)
 762 {
 763         get_object_details();
 764         sorted_by_type = create_sorted_list(type_size_sort);
 765         if (window && depth)
 766                 find_deltas(sorted_by_type, window+1, depth);
 767 }
 768
 769 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
 770 {
 771         static const char cache[] = "pack-cache/pack-%s.%s";
 772         char *cached_pack, *cached_idx;
 773         int ifd, ofd, ifd_ix = -1;
 774
 775         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
 776         ifd = open(cached_pack, O_RDONLY);
 777         if (ifd < 0)
 778                 return 0;
 779
 780         if (!pack_to_stdout) {
 781                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
 782                 ifd_ix = open(cached_idx, O_RDONLY);
 783                 if (ifd_ix < 0) {
 784                         close(ifd);
 785                         return 0;
 786                 }
 787         }
 788
 789         if (progress)
 790                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
 791                         sha1_to_hex(sha1));
 792
 793         if (pack_to_stdout) {
 794                 if (copy_fd(ifd, 1))
 795                         exit(1);
 796                 close(ifd);
 797         }
 798         else {
 799                 char name[PATH_MAX];
 800                 snprintf(name, sizeof(name),
 801                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
 802                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
 803                 if (ofd < 0)
 804                         die("unable to open %s (%s)", name, strerror(errno));
 805                 if (copy_fd(ifd, ofd))
 806                         exit(1);
 807                 close(ifd);
 808
 809                 snprintf(name, sizeof(name),
 810                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
 811                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
 812                 if (ofd < 0)
 813                         die("unable to open %s (%s)", name, strerror(errno));
 814                 if (copy_fd(ifd_ix, ofd))
 815                         exit(1);
 816                 close(ifd_ix);
 817                 puts(sha1_to_hex(sha1));
 818         }
 819
 820         return 1;
 821 }
 822
 823 int main(int argc, char **argv)
 824 {
 825         SHA_CTX ctx;
 826         char line[PATH_MAX + 20];
 827         int window = 10, depth = 10, pack_to_stdout = 0;
 828         struct object_entry **list;
 829         int i;
 830
 831         setup_git_directory();
 832
 833         for (i = 1; i < argc; i++) {
 834                 const char *arg = argv[i];
 835
 836                 if (*arg == '-') {
 837                         if (!strcmp("--non-empty", arg)) {
 838                                 non_empty = 1;
 839                                 continue;
 840                         }
 841                         if (!strcmp("--local", arg)) {
 842                                 local = 1;
 843                                 continue;
 844                         }
 845                         if (!strcmp("--incremental", arg)) {
 846                                 incremental = 1;
 847                                 continue;
 848                         }
 849                         if (!strncmp("--window=", arg, 9)) {
 850                                 char *end;
 851                                 window = strtoul(arg+9, &end, 0);
 852                                 if (!arg[9] || *end)
 853                                         usage(pack_usage);
 854                                 continue;
 855                         }
 856                         if (!strncmp("--depth=", arg, 8)) {
 857                                 char *end;
 858                                 depth = strtoul(arg+8, &end, 0);
 859                                 if (!arg[8] || *end)
 860                                         usage(pack_usage);
 861                                 continue;
 862                         }
 863                         if (!strcmp("-q", arg)) {
 864                                 progress = 0;
 865                                 continue;
 866                         }
 867                         if (!strcmp("--no-reuse-delta", arg)) {
 868                                 no_reuse_delta = 1;
 869                                 continue;
 870                         }
 871                         if (!strcmp("--stdout", arg)) {
 872                                 pack_to_stdout = 1;
 873                                 continue;
 874                         }
 875                         usage(pack_usage);
 876                 }
 877                 if (base_name)
 878                         usage(pack_usage);
 879                 base_name = arg;
 880         }
 881
 882         if (pack_to_stdout != !base_name)
 883                 usage(pack_usage);
 884
 885         prepare_packed_git();
 886
 887         if (progress) {
 888                 struct itimerval v;
 889                 v.it_interval.tv_sec = 1;
 890                 v.it_interval.tv_usec = 0;
 891                 v.it_value = v.it_interval;
 892                 signal(SIGALRM, progress_interval);
 893                 setitimer(ITIMER_REAL, &v, NULL);
 894                 fprintf(stderr, "Generating pack...\n");
 895         }
 896
 897         while (fgets(line, sizeof(line), stdin) != NULL) {
 898                 unsigned int hash;
 899                 char *p;
 900                 unsigned char sha1[20];
 901
 902                 if (progress_update) {
 903                         fprintf(stderr, "Counting objects...%d\r", nr_objects);
 904                         progress_update = 0;
 905                 }
 906                 if (get_sha1_hex(line, sha1))
 907                         die("expected sha1, got garbage:\n %s", line);
 908                 hash = 0;
 909                 p = line+40;
 910                 while (*p) {
 911                         unsigned char c = *p++;
 912                         if (isspace(c))
 913                                 continue;
 914                         hash = hash * 11 + c;
 915                 }
 916                 add_object_entry(sha1, hash);
 917         }
 918         if (progress)
 919                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
 920         if (non_empty && !nr_objects)
 921                 return 0;
 922
 923         sorted_by_sha = create_sorted_list(sha1_sort);
 924         SHA1_Init(&ctx);
 925         list = sorted_by_sha;
 926         for (i = 0; i < nr_objects; i++) {
 927                 struct object_entry *entry = *list++;
 928                 SHA1_Update(&ctx, entry->sha1, 20);
 929         }
 930         SHA1_Final(object_list_sha1, &ctx);
 931
 932         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
 933                 ;
 934         else {
 935                 prepare_pack(window, depth);
 936                 if (progress && pack_to_stdout) {
 937                         /* the other end usually displays progress itself */
 938                         struct itimerval v = {{0,},};
 939                         setitimer(ITIMER_REAL, &v, NULL);
 940                         signal(SIGALRM, SIG_IGN );
 941                         progress_update = 0;
 942                 }
 943                 write_pack_file();
 944                 if (!pack_to_stdout) {
 945                         write_index_file();
 946                         puts(sha1_to_hex(object_list_sha1));
 947                 }
 948         }
 949         if (progress)
 950                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
 951                         nr_objects, written, written_delta, reused, reused_delta);
 952         return 0;
 953 }