git.oblomov.eu Git - git/blob - builtin-pack-objects.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "object.h"
   4 #include "blob.h"
   5 #include "commit.h"
   6 #include "tag.h"
   7 #include "tree.h"
   8 #include "delta.h"
   9 #include "pack.h"
  10 #include "csum-file.h"
  11 #include "tree-walk.h"
  12 #include <sys/time.h>
  13 #include <signal.h>
  14
  15 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";
  16
  17 struct object_entry {
  18         unsigned char sha1[20];
  19         unsigned long size;     /* uncompressed size */
  20         unsigned long offset;   /* offset into the final pack file;
  21                                  * nonzero if already written.
  22                                  */
  23         unsigned int depth;     /* delta depth */
  24         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  25         unsigned int hash;      /* name hint hash */
  26         enum object_type type;
  27         enum object_type in_pack_type;  /* could be delta */
  28         unsigned long delta_size;       /* delta data size (uncompressed) */
  29         struct object_entry *delta;     /* delta base object */
  30         struct packed_git *in_pack;     /* already in pack */
  31         unsigned int in_pack_offset;
  32         struct object_entry *delta_child; /* deltified objects who bases me */
  33         struct object_entry *delta_sibling; /* other deltified objects who
  34                                              * uses the same base as me
  35                                              */
  36         int preferred_base;     /* we do not pack this, but is encouraged to
  37                                  * be used as the base objectto delta huge
  38                                  * objects against.
  39                                  */
  40 };
  41
  42 /*
  43  * Objects we are going to pack are collected in objects array (dynamically
  44  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  45  * in the order we see -- typically rev-list --objects order that gives us
  46  * nice "minimum seek" order.
  47  *
  48  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  49  * elements in the objects array.  The former is used to build the pack
  50  * index (lists object names in the ascending order to help offset lookup),
  51  * and the latter is used to group similar things together by try_delta()
  52  * heuristics.
  53  */
  54
  55 static unsigned char object_list_sha1[20];
  56 static int non_empty;
  57 static int no_reuse_delta;
  58 static int local;
  59 static int incremental;
  60 static struct object_entry **sorted_by_sha, **sorted_by_type;
  61 static struct object_entry *objects;
  62 static int nr_objects, nr_alloc, nr_result;
  63 static const char *base_name;
  64 static unsigned char pack_file_sha1[20];
  65 static int progress = 1;
  66 static volatile sig_atomic_t progress_update;
  67 static int window = 10;
  68
  69 /*
  70  * The object names in objects array are hashed with this hashtable,
  71  * to help looking up the entry by object name.  Binary search from
  72  * sorted_by_sha is also possible but this was easier to code and faster.
  73  * This hashtable is built after all the objects are seen.
  74  */
  75 static int *object_ix;
  76 static int object_ix_hashsz;
  77
  78 /*
  79  * Pack index for existing packs give us easy access to the offsets into
  80  * corresponding pack file where each object's data starts, but the entries
  81  * do not store the size of the compressed representation (uncompressed
  82  * size is easily available by examining the pack entry header).  We build
  83  * a hashtable of existing packs (pack_revindex), and keep reverse index
  84  * here -- pack index file is sorted by object name mapping to offset; this
  85  * pack_revindex[].revindex array is an ordered list of offsets, so if you
  86  * know the offset of an object, next offset is where its packed
  87  * representation ends.
  88  */
  89 struct pack_revindex {
  90         struct packed_git *p;
  91         unsigned long *revindex;
  92 } *pack_revindex = NULL;
  93 static int pack_revindex_hashsz;
  94
  95 /*
  96  * stats
  97  */
  98 static int written;
  99 static int written_delta;
 100 static int reused;
 101 static int reused_delta;
 102
 103 static int pack_revindex_ix(struct packed_git *p)
 104 {
 105         unsigned long ui = (unsigned long)p;
 106         int i;
 107
 108         ui = ui ^ (ui >> 16); /* defeat structure alignment */
 109         i = (int)(ui % pack_revindex_hashsz);
 110         while (pack_revindex[i].p) {
 111                 if (pack_revindex[i].p == p)
 112                         return i;
 113                 if (++i == pack_revindex_hashsz)
 114                         i = 0;
 115         }
 116         return -1 - i;
 117 }
 118
 119 static void prepare_pack_ix(void)
 120 {
 121         int num;
 122         struct packed_git *p;
 123         for (num = 0, p = packed_git; p; p = p->next)
 124                 num++;
 125         if (!num)
 126                 return;
 127         pack_revindex_hashsz = num * 11;
 128         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 129         for (p = packed_git; p; p = p->next) {
 130                 num = pack_revindex_ix(p);
 131                 num = - 1 - num;
 132                 pack_revindex[num].p = p;
 133         }
 134         /* revindex elements are lazily initialized */
 135 }
 136
 137 static int cmp_offset(const void *a_, const void *b_)
 138 {
 139         unsigned long a = *(unsigned long *) a_;
 140         unsigned long b = *(unsigned long *) b_;
 141         if (a < b)
 142                 return -1;
 143         else if (a == b)
 144                 return 0;
 145         else
 146                 return 1;
 147 }
 148
 149 /*
 150  * Ordered list of offsets of objects in the pack.
 151  */
 152 static void prepare_pack_revindex(struct pack_revindex *rix)
 153 {
 154         struct packed_git *p = rix->p;
 155         int num_ent = num_packed_objects(p);
 156         int i;
 157         void *index = p->index_base + 256;
 158
 159         rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
 160         for (i = 0; i < num_ent; i++) {
 161                 unsigned int hl = *((unsigned int *)((char *) index + 24*i));
 162                 rix->revindex[i] = ntohl(hl);
 163         }
 164         /* This knows the pack format -- the 20-byte trailer
 165          * follows immediately after the last object data.
 166          */
 167         rix->revindex[num_ent] = p->pack_size - 20;
 168         qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
 169 }
 170
 171 static unsigned long find_packed_object_size(struct packed_git *p,
 172                                              unsigned long ofs)
 173 {
 174         int num;
 175         int lo, hi;
 176         struct pack_revindex *rix;
 177         unsigned long *revindex;
 178         num = pack_revindex_ix(p);
 179         if (num < 0)
 180                 die("internal error: pack revindex uninitialized");
 181         rix = &pack_revindex[num];
 182         if (!rix->revindex)
 183                 prepare_pack_revindex(rix);
 184         revindex = rix->revindex;
 185         lo = 0;
 186         hi = num_packed_objects(p) + 1;
 187         do {
 188                 int mi = (lo + hi) / 2;
 189                 if (revindex[mi] == ofs) {
 190                         return revindex[mi+1] - ofs;
 191                 }
 192                 else if (ofs < revindex[mi])
 193                         hi = mi;
 194                 else
 195                         lo = mi + 1;
 196         } while (lo < hi);
 197         die("internal error: pack revindex corrupt");
 198 }
 199
 200 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 201 {
 202         unsigned long othersize, delta_size;
 203         char type[10];
 204         void *otherbuf = read_sha1_file(entry->delta->sha1, type, &othersize);
 205         void *delta_buf;
 206
 207         if (!otherbuf)
 208                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 209         delta_buf = diff_delta(otherbuf, othersize,
 210                                buf, size, &delta_size, 0);
 211         if (!delta_buf || delta_size != entry->delta_size)
 212                 die("delta size changed");
 213         free(buf);
 214         free(otherbuf);
 215         return delta_buf;
 216 }
 217
 218 /*
 219  * The per-object header is a pretty dense thing, which is
 220  *  - first byte: low four bits are "size", then three bits of "type",
 221  *    and the high bit is "size continues".
 222  *  - each byte afterwards: low seven bits are size continuation,
 223  *    with the high bit being "size continues"
 224  */
 225 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 226 {
 227         int n = 1;
 228         unsigned char c;
 229
 230         if (type < OBJ_COMMIT || type > OBJ_DELTA)
 231                 die("bad type %d", type);
 232
 233         c = (type << 4) | (size & 15);
 234         size >>= 4;
 235         while (size) {
 236                 *hdr++ = c | 0x80;
 237                 c = size & 0x7f;
 238                 size >>= 7;
 239                 n++;
 240         }
 241         *hdr = c;
 242         return n;
 243 }
 244
 245 static unsigned long write_object(struct sha1file *f,
 246                                   struct object_entry *entry)
 247 {
 248         unsigned long size;
 249         char type[10];
 250         void *buf;
 251         unsigned char header[10];
 252         unsigned hdrlen, datalen;
 253         enum object_type obj_type;
 254         int to_reuse = 0;
 255
 256         if (entry->preferred_base)
 257                 return 0;
 258
 259         obj_type = entry->type;
 260         if (! entry->in_pack)
 261                 to_reuse = 0;   /* can't reuse what we don't have */
 262         else if (obj_type == OBJ_DELTA)
 263                 to_reuse = 1;   /* check_object() decided it for us */
 264         else if (obj_type != entry->in_pack_type)
 265                 to_reuse = 0;   /* pack has delta which is unusable */
 266         else if (entry->delta)
 267                 to_reuse = 0;   /* we want to pack afresh */
 268         else
 269                 to_reuse = 1;   /* we have it in-pack undeltified,
 270                                  * and we do not need to deltify it.
 271                                  */
 272
 273         if (!entry->in_pack && !entry->delta) {
 274                 unsigned char *map;
 275                 unsigned long mapsize;
 276                 map = map_sha1_file(entry->sha1, &mapsize);
 277                 if (map && !legacy_loose_object(map)) {
 278                         /* We can copy straight into the pack file */
 279                         sha1write(f, map, mapsize);
 280                         munmap(map, mapsize);
 281                         written++;
 282                         reused++;
 283                         return mapsize;
 284                 }
 285                 if (map)
 286                         munmap(map, mapsize);
 287         }
 288
 289         if (! to_reuse) {
 290                 buf = read_sha1_file(entry->sha1, type, &size);
 291                 if (!buf)
 292                         die("unable to read %s", sha1_to_hex(entry->sha1));
 293                 if (size != entry->size)
 294                         die("object %s size inconsistency (%lu vs %lu)",
 295                             sha1_to_hex(entry->sha1), size, entry->size);
 296                 if (entry->delta) {
 297                         buf = delta_against(buf, size, entry);
 298                         size = entry->delta_size;
 299                         obj_type = OBJ_DELTA;
 300                 }
 301                 /*
 302                  * The object header is a byte of 'type' followed by zero or
 303                  * more bytes of length.  For deltas, the 20 bytes of delta
 304                  * sha1 follows that.
 305                  */
 306                 hdrlen = encode_header(obj_type, size, header);
 307                 sha1write(f, header, hdrlen);
 308
 309                 if (entry->delta) {
 310                         sha1write(f, entry->delta, 20);
 311                         hdrlen += 20;
 312                 }
 313                 datalen = sha1write_compressed(f, buf, size);
 314                 free(buf);
 315         }
 316         else {
 317                 struct packed_git *p = entry->in_pack;
 318                 use_packed_git(p);
 319
 320                 datalen = find_packed_object_size(p, entry->in_pack_offset);
 321                 buf = (char *) p->pack_base + entry->in_pack_offset;
 322                 sha1write(f, buf, datalen);
 323                 unuse_packed_git(p);
 324                 hdrlen = 0; /* not really */
 325                 if (obj_type == OBJ_DELTA)
 326                         reused_delta++;
 327                 reused++;
 328         }
 329         if (obj_type == OBJ_DELTA)
 330                 written_delta++;
 331         written++;
 332         return hdrlen + datalen;
 333 }
 334
 335 static unsigned long write_one(struct sha1file *f,
 336                                struct object_entry *e,
 337                                unsigned long offset)
 338 {
 339         if (e->offset)
 340                 /* offset starts from header size and cannot be zero
 341                  * if it is written already.
 342                  */
 343                 return offset;
 344         e->offset = offset;
 345         offset += write_object(f, e);
 346         /* if we are deltified, write out its base object. */
 347         if (e->delta)
 348                 offset = write_one(f, e->delta, offset);
 349         return offset;
 350 }
 351
 352 static void write_pack_file(void)
 353 {
 354         int i;
 355         struct sha1file *f;
 356         unsigned long offset;
 357         struct pack_header hdr;
 358         unsigned last_percent = 999;
 359         int do_progress = 0;
 360
 361         if (!base_name)
 362                 f = sha1fd(1, "<stdout>");
 363         else {
 364                 f = sha1create("%s-%s.%s", base_name,
 365                                sha1_to_hex(object_list_sha1), "pack");
 366                 do_progress = progress;
 367         }
 368         if (do_progress)
 369                 fprintf(stderr, "Writing %d objects.\n", nr_result);
 370
 371         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 372         hdr.hdr_version = htonl(PACK_VERSION);
 373         hdr.hdr_entries = htonl(nr_result);
 374         sha1write(f, &hdr, sizeof(hdr));
 375         offset = sizeof(hdr);
 376         if (!nr_result)
 377                 goto done;
 378         for (i = 0; i < nr_objects; i++) {
 379                 offset = write_one(f, objects + i, offset);
 380                 if (do_progress) {
 381                         unsigned percent = written * 100 / nr_result;
 382                         if (progress_update || percent != last_percent) {
 383                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 384                                         percent, written, nr_result);
 385                                 progress_update = 0;
 386                                 last_percent = percent;
 387                         }
 388                 }
 389         }
 390         if (do_progress)
 391                 fputc('\n', stderr);
 392  done:
 393         sha1close(f, pack_file_sha1, 1);
 394 }
 395
 396 static void write_index_file(void)
 397 {
 398         int i;
 399         struct sha1file *f = sha1create("%s-%s.%s", base_name,
 400                                         sha1_to_hex(object_list_sha1), "idx");
 401         struct object_entry **list = sorted_by_sha;
 402         struct object_entry **last = list + nr_result;
 403         unsigned int array[256];
 404
 405         /*
 406          * Write the first-level table (the list is sorted,
 407          * but we use a 256-entry lookup to be able to avoid
 408          * having to do eight extra binary search iterations).
 409          */
 410         for (i = 0; i < 256; i++) {
 411                 struct object_entry **next = list;
 412                 while (next < last) {
 413                         struct object_entry *entry = *next;
 414                         if (entry->sha1[0] != i)
 415                                 break;
 416                         next++;
 417                 }
 418                 array[i] = htonl(next - sorted_by_sha);
 419                 list = next;
 420         }
 421         sha1write(f, array, 256 * sizeof(int));
 422
 423         /*
 424          * Write the actual SHA1 entries..
 425          */
 426         list = sorted_by_sha;
 427         for (i = 0; i < nr_result; i++) {
 428                 struct object_entry *entry = *list++;
 429                 unsigned int offset = htonl(entry->offset);
 430                 sha1write(f, &offset, 4);
 431                 sha1write(f, entry->sha1, 20);
 432         }
 433         sha1write(f, pack_file_sha1, 20);
 434         sha1close(f, NULL, 1);
 435 }
 436
 437 static int locate_object_entry_hash(const unsigned char *sha1)
 438 {
 439         int i;
 440         unsigned int ui;
 441         memcpy(&ui, sha1, sizeof(unsigned int));
 442         i = ui % object_ix_hashsz;
 443         while (0 < object_ix[i]) {
 444                 if (!hashcmp(sha1, objects[object_ix[i] - 1].sha1))
 445                         return i;
 446                 if (++i == object_ix_hashsz)
 447                         i = 0;
 448         }
 449         return -1 - i;
 450 }
 451
 452 static struct object_entry *locate_object_entry(const unsigned char *sha1)
 453 {
 454         int i;
 455
 456         if (!object_ix_hashsz)
 457                 return NULL;
 458
 459         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 rehash_objects(void)
 466 {
 467         int i;
 468         struct object_entry *oe;
 469
 470         object_ix_hashsz = nr_objects * 3;
 471         if (object_ix_hashsz < 1024)
 472                 object_ix_hashsz = 1024;
 473         object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 474         memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 475         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 476                 int ix = locate_object_entry_hash(oe->sha1);
 477                 if (0 <= ix)
 478                         continue;
 479                 ix = -1 - ix;
 480                 object_ix[ix] = i + 1;
 481         }
 482 }
 483
 484 static unsigned name_hash(const char *name)
 485 {
 486         unsigned char c;
 487         unsigned hash = 0;
 488
 489         /*
 490          * This effectively just creates a sortable number from the
 491          * last sixteen non-whitespace characters. Last characters
 492          * count "most", so things that end in ".c" sort together.
 493          */
 494         while ((c = *name++) != 0) {
 495                 if (isspace(c))
 496                         continue;
 497                 hash = (hash >> 2) + (c << 24);
 498         }
 499         return hash;
 500 }
 501
 502 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 503 {
 504         unsigned int idx = nr_objects;
 505         struct object_entry *entry;
 506         struct packed_git *p;
 507         unsigned int found_offset = 0;
 508         struct packed_git *found_pack = NULL;
 509         int ix, status = 0;
 510
 511         if (!exclude) {
 512                 for (p = packed_git; p; p = p->next) {
 513                         struct pack_entry e;
 514                         if (find_pack_entry_one(sha1, &e, p)) {
 515                                 if (incremental)
 516                                         return 0;
 517                                 if (local && !p->pack_local)
 518                                         return 0;
 519                                 if (!found_pack) {
 520                                         found_offset = e.offset;
 521                                         found_pack = e.p;
 522                                 }
 523                         }
 524                 }
 525         }
 526         if ((entry = locate_object_entry(sha1)) != NULL)
 527                 goto already_added;
 528
 529         if (idx >= nr_alloc) {
 530                 unsigned int needed = (idx + 1024) * 3 / 2;
 531                 objects = xrealloc(objects, needed * sizeof(*entry));
 532                 nr_alloc = needed;
 533         }
 534         entry = objects + idx;
 535         nr_objects = idx + 1;
 536         memset(entry, 0, sizeof(*entry));
 537         hashcpy(entry->sha1, sha1);
 538         entry->hash = hash;
 539
 540         if (object_ix_hashsz * 3 <= nr_objects * 4)
 541                 rehash_objects();
 542         else {
 543                 ix = locate_object_entry_hash(entry->sha1);
 544                 if (0 <= ix)
 545                         die("internal error in object hashing.");
 546                 object_ix[-1 - ix] = idx + 1;
 547         }
 548         status = 1;
 549
 550  already_added:
 551         if (progress_update) {
 552                 fprintf(stderr, "Counting objects...%d\r", nr_objects);
 553                 progress_update = 0;
 554         }
 555         if (exclude)
 556                 entry->preferred_base = 1;
 557         else {
 558                 if (found_pack) {
 559                         entry->in_pack = found_pack;
 560                         entry->in_pack_offset = found_offset;
 561                 }
 562         }
 563         return status;
 564 }
 565
 566 struct pbase_tree_cache {
 567         unsigned char sha1[20];
 568         int ref;
 569         int temporary;
 570         void *tree_data;
 571         unsigned long tree_size;
 572 };
 573
 574 static struct pbase_tree_cache *(pbase_tree_cache[256]);
 575 static int pbase_tree_cache_ix(const unsigned char *sha1)
 576 {
 577         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 578 }
 579 static int pbase_tree_cache_ix_incr(int ix)
 580 {
 581         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 582 }
 583
 584 static struct pbase_tree {
 585         struct pbase_tree *next;
 586         /* This is a phony "cache" entry; we are not
 587          * going to evict it nor find it through _get()
 588          * mechanism -- this is for the toplevel node that
 589          * would almost always change with any commit.
 590          */
 591         struct pbase_tree_cache pcache;
 592 } *pbase_tree;
 593
 594 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 595 {
 596         struct pbase_tree_cache *ent, *nent;
 597         void *data;
 598         unsigned long size;
 599         char type[20];
 600         int neigh;
 601         int my_ix = pbase_tree_cache_ix(sha1);
 602         int available_ix = -1;
 603
 604         /* pbase-tree-cache acts as a limited hashtable.
 605          * your object will be found at your index or within a few
 606          * slots after that slot if it is cached.
 607          */
 608         for (neigh = 0; neigh < 8; neigh++) {
 609                 ent = pbase_tree_cache[my_ix];
 610                 if (ent && !hashcmp(ent->sha1, sha1)) {
 611                         ent->ref++;
 612                         return ent;
 613                 }
 614                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 615                          ((0 <= available_ix) &&
 616                           (!ent && pbase_tree_cache[available_ix])))
 617                         available_ix = my_ix;
 618                 if (!ent)
 619                         break;
 620                 my_ix = pbase_tree_cache_ix_incr(my_ix);
 621         }
 622
 623         /* Did not find one.  Either we got a bogus request or
 624          * we need to read and perhaps cache.
 625          */
 626         data = read_sha1_file(sha1, type, &size);
 627         if (!data)
 628                 return NULL;
 629         if (strcmp(type, tree_type)) {
 630                 free(data);
 631                 return NULL;
 632         }
 633
 634         /* We need to either cache or return a throwaway copy */
 635
 636         if (available_ix < 0)
 637                 ent = NULL;
 638         else {
 639                 ent = pbase_tree_cache[available_ix];
 640                 my_ix = available_ix;
 641         }
 642
 643         if (!ent) {
 644                 nent = xmalloc(sizeof(*nent));
 645                 nent->temporary = (available_ix < 0);
 646         }
 647         else {
 648                 /* evict and reuse */
 649                 free(ent->tree_data);
 650                 nent = ent;
 651         }
 652         hashcpy(nent->sha1, sha1);
 653         nent->tree_data = data;
 654         nent->tree_size = size;
 655         nent->ref = 1;
 656         if (!nent->temporary)
 657                 pbase_tree_cache[my_ix] = nent;
 658         return nent;
 659 }
 660
 661 static void pbase_tree_put(struct pbase_tree_cache *cache)
 662 {
 663         if (!cache->temporary) {
 664                 cache->ref--;
 665                 return;
 666         }
 667         free(cache->tree_data);
 668         free(cache);
 669 }
 670
 671 static int name_cmp_len(const char *name)
 672 {
 673         int i;
 674         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 675                 ;
 676         return i;
 677 }
 678
 679 static void add_pbase_object(struct tree_desc *tree,
 680                              const char *name,
 681                              int cmplen,
 682                              const char *fullname)
 683 {
 684         struct name_entry entry;
 685
 686         while (tree_entry(tree,&entry)) {
 687                 unsigned long size;
 688                 char type[20];
 689
 690                 if (entry.pathlen != cmplen ||
 691                     memcmp(entry.path, name, cmplen) ||
 692                     !has_sha1_file(entry.sha1) ||
 693                     sha1_object_info(entry.sha1, type, &size))
 694                         continue;
 695                 if (name[cmplen] != '/') {
 696                         unsigned hash = name_hash(fullname);
 697                         add_object_entry(entry.sha1, hash, 1);
 698                         return;
 699                 }
 700                 if (!strcmp(type, tree_type)) {
 701                         struct tree_desc sub;
 702                         struct pbase_tree_cache *tree;
 703                         const char *down = name+cmplen+1;
 704                         int downlen = name_cmp_len(down);
 705
 706                         tree = pbase_tree_get(entry.sha1);
 707                         if (!tree)
 708                                 return;
 709                         sub.buf = tree->tree_data;
 710                         sub.size = tree->tree_size;
 711
 712                         add_pbase_object(&sub, down, downlen, fullname);
 713                         pbase_tree_put(tree);
 714                 }
 715         }
 716 }
 717
 718 static unsigned *done_pbase_paths;
 719 static int done_pbase_paths_num;
 720 static int done_pbase_paths_alloc;
 721 static int done_pbase_path_pos(unsigned hash)
 722 {
 723         int lo = 0;
 724         int hi = done_pbase_paths_num;
 725         while (lo < hi) {
 726                 int mi = (hi + lo) / 2;
 727                 if (done_pbase_paths[mi] == hash)
 728                         return mi;
 729                 if (done_pbase_paths[mi] < hash)
 730                         hi = mi;
 731                 else
 732                         lo = mi + 1;
 733         }
 734         return -lo-1;
 735 }
 736
 737 static int check_pbase_path(unsigned hash)
 738 {
 739         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
 740         if (0 <= pos)
 741                 return 1;
 742         pos = -pos - 1;
 743         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
 744                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
 745                 done_pbase_paths = xrealloc(done_pbase_paths,
 746                                             done_pbase_paths_alloc *
 747                                             sizeof(unsigned));
 748         }
 749         done_pbase_paths_num++;
 750         if (pos < done_pbase_paths_num)
 751                 memmove(done_pbase_paths + pos + 1,
 752                         done_pbase_paths + pos,
 753                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
 754         done_pbase_paths[pos] = hash;
 755         return 0;
 756 }
 757
 758 static void add_preferred_base_object(char *name, unsigned hash)
 759 {
 760         struct pbase_tree *it;
 761         int cmplen = name_cmp_len(name);
 762
 763         if (check_pbase_path(hash))
 764                 return;
 765
 766         for (it = pbase_tree; it; it = it->next) {
 767                 if (cmplen == 0) {
 768                         hash = name_hash("");
 769                         add_object_entry(it->pcache.sha1, hash, 1);
 770                 }
 771                 else {
 772                         struct tree_desc tree;
 773                         tree.buf = it->pcache.tree_data;
 774                         tree.size = it->pcache.tree_size;
 775                         add_pbase_object(&tree, name, cmplen, name);
 776                 }
 777         }
 778 }
 779
 780 static void add_preferred_base(unsigned char *sha1)
 781 {
 782         struct pbase_tree *it;
 783         void *data;
 784         unsigned long size;
 785         unsigned char tree_sha1[20];
 786
 787         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
 788         if (!data)
 789                 return;
 790
 791         for (it = pbase_tree; it; it = it->next) {
 792                 if (!hashcmp(it->pcache.sha1, tree_sha1)) {
 793                         free(data);
 794                         return;
 795                 }
 796         }
 797
 798         it = xcalloc(1, sizeof(*it));
 799         it->next = pbase_tree;
 800         pbase_tree = it;
 801
 802         hashcpy(it->pcache.sha1, tree_sha1);
 803         it->pcache.tree_data = data;
 804         it->pcache.tree_size = size;
 805 }
 806
 807 static void check_object(struct object_entry *entry)
 808 {
 809         char type[20];
 810
 811         if (entry->in_pack && !entry->preferred_base) {
 812                 unsigned char base[20];
 813                 unsigned long size;
 814                 struct object_entry *base_entry;
 815
 816                 /* We want in_pack_type even if we do not reuse delta.
 817                  * There is no point not reusing non-delta representations.
 818                  */
 819                 check_reuse_pack_delta(entry->in_pack,
 820                                        entry->in_pack_offset,
 821                                        base, &size,
 822                                        &entry->in_pack_type);
 823
 824                 /* Check if it is delta, and the base is also an object
 825                  * we are going to pack.  If so we will reuse the existing
 826                  * delta.
 827                  */
 828                 if (!no_reuse_delta &&
 829                     entry->in_pack_type == OBJ_DELTA &&
 830                     (base_entry = locate_object_entry(base)) &&
 831                     (!base_entry->preferred_base)) {
 832
 833                         /* Depth value does not matter - find_deltas()
 834                          * will never consider reused delta as the
 835                          * base object to deltify other objects
 836                          * against, in order to avoid circular deltas.
 837                          */
 838
 839                         /* uncompressed size of the delta data */
 840                         entry->size = entry->delta_size = size;
 841                         entry->delta = base_entry;
 842                         entry->type = OBJ_DELTA;
 843
 844                         entry->delta_sibling = base_entry->delta_child;
 845                         base_entry->delta_child = entry;
 846
 847                         return;
 848                 }
 849                 /* Otherwise we would do the usual */
 850         }
 851
 852         if (sha1_object_info(entry->sha1, type, &entry->size))
 853                 die("unable to get type of object %s",
 854                     sha1_to_hex(entry->sha1));
 855
 856         if (!strcmp(type, commit_type)) {
 857                 entry->type = OBJ_COMMIT;
 858         } else if (!strcmp(type, tree_type)) {
 859                 entry->type = OBJ_TREE;
 860         } else if (!strcmp(type, blob_type)) {
 861                 entry->type = OBJ_BLOB;
 862         } else if (!strcmp(type, tag_type)) {
 863                 entry->type = OBJ_TAG;
 864         } else
 865                 die("unable to pack object %s of type %s",
 866                     sha1_to_hex(entry->sha1), type);
 867 }
 868
 869 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
 870 {
 871         struct object_entry *child = me->delta_child;
 872         unsigned int m = n;
 873         while (child) {
 874                 unsigned int c = check_delta_limit(child, n + 1);
 875                 if (m < c)
 876                         m = c;
 877                 child = child->delta_sibling;
 878         }
 879         return m;
 880 }
 881
 882 static void get_object_details(void)
 883 {
 884         int i;
 885         struct object_entry *entry;
 886
 887         prepare_pack_ix();
 888         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 889                 check_object(entry);
 890
 891         if (nr_objects == nr_result) {
 892                 /*
 893                  * Depth of objects that depend on the entry -- this
 894                  * is subtracted from depth-max to break too deep
 895                  * delta chain because of delta data reusing.
 896                  * However, we loosen this restriction when we know we
 897                  * are creating a thin pack -- it will have to be
 898                  * expanded on the other end anyway, so do not
 899                  * artificially cut the delta chain and let it go as
 900                  * deep as it wants.
 901                  */
 902                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
 903                         if (!entry->delta && entry->delta_child)
 904                                 entry->delta_limit =
 905                                         check_delta_limit(entry, 1);
 906         }
 907 }
 908
 909 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
 910
 911 static entry_sort_t current_sort;
 912
 913 static int sort_comparator(const void *_a, const void *_b)
 914 {
 915         struct object_entry *a = *(struct object_entry **)_a;
 916         struct object_entry *b = *(struct object_entry **)_b;
 917         return current_sort(a,b);
 918 }
 919
 920 static struct object_entry **create_sorted_list(entry_sort_t sort)
 921 {
 922         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
 923         int i;
 924
 925         for (i = 0; i < nr_objects; i++)
 926                 list[i] = objects + i;
 927         current_sort = sort;
 928         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
 929         return list;
 930 }
 931
 932 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
 933 {
 934         return hashcmp(a->sha1, b->sha1);
 935 }
 936
 937 static struct object_entry **create_final_object_list(void)
 938 {
 939         struct object_entry **list;
 940         int i, j;
 941
 942         for (i = nr_result = 0; i < nr_objects; i++)
 943                 if (!objects[i].preferred_base)
 944                         nr_result++;
 945         list = xmalloc(nr_result * sizeof(struct object_entry *));
 946         for (i = j = 0; i < nr_objects; i++) {
 947                 if (!objects[i].preferred_base)
 948                         list[j++] = objects + i;
 949         }
 950         current_sort = sha1_sort;
 951         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
 952         return list;
 953 }
 954
 955 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
 956 {
 957         if (a->type < b->type)
 958                 return -1;
 959         if (a->type > b->type)
 960                 return 1;
 961         if (a->hash < b->hash)
 962                 return -1;
 963         if (a->hash > b->hash)
 964                 return 1;
 965         if (a->preferred_base < b->preferred_base)
 966                 return -1;
 967         if (a->preferred_base > b->preferred_base)
 968                 return 1;
 969         if (a->size < b->size)
 970                 return -1;
 971         if (a->size > b->size)
 972                 return 1;
 973         return a < b ? -1 : (a > b);
 974 }
 975
 976 struct unpacked {
 977         struct object_entry *entry;
 978         void *data;
 979         struct delta_index *index;
 980 };
 981
 982 /*
 983  * We search for deltas _backwards_ in a list sorted by type and
 984  * by size, so that we see progressively smaller and smaller files.
 985  * That's because we prefer deltas to be from the bigger file
 986  * to the smaller - deletes are potentially cheaper, but perhaps
 987  * more importantly, the bigger file is likely the more recent
 988  * one.
 989  */
 990 static int try_delta(struct unpacked *trg, struct unpacked *src,
 991                      unsigned max_depth)
 992 {
 993         struct object_entry *trg_entry = trg->entry;
 994         struct object_entry *src_entry = src->entry;
 995         unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
 996         char type[10];
 997         void *delta_buf;
 998
 999         /* Don't bother doing diffs between different types */
1000         if (trg_entry->type != src_entry->type)
1001                 return -1;
1002
1003         /* We do not compute delta to *create* objects we are not
1004          * going to pack.
1005          */
1006         if (trg_entry->preferred_base)
1007                 return -1;
1008
1009         /*
1010          * We do not bother to try a delta that we discarded
1011          * on an earlier try, but only when reusing delta data.
1012          */
1013         if (!no_reuse_delta && trg_entry->in_pack &&
1014             trg_entry->in_pack == src_entry->in_pack)
1015                 return 0;
1016
1017         /*
1018          * If the current object is at pack edge, take the depth the
1019          * objects that depend on the current object into account --
1020          * otherwise they would become too deep.
1021          */
1022         if (trg_entry->delta_child) {
1023                 if (max_depth <= trg_entry->delta_limit)
1024                         return 0;
1025                 max_depth -= trg_entry->delta_limit;
1026         }
1027         if (src_entry->depth >= max_depth)
1028                 return 0;
1029
1030         /* Now some size filtering heuristics. */
1031         trg_size = trg_entry->size;
1032         max_size = trg_size/2 - 20;
1033         max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1034         if (max_size == 0)
1035                 return 0;
1036         if (trg_entry->delta && trg_entry->delta_size <= max_size)
1037                 max_size = trg_entry->delta_size-1;
1038         src_size = src_entry->size;
1039         sizediff = src_size < trg_size ? trg_size - src_size : 0;
1040         if (sizediff >= max_size)
1041                 return 0;
1042
1043         /* Load data if not already done */
1044         if (!trg->data) {
1045                 trg->data = read_sha1_file(trg_entry->sha1, type, &sz);
1046                 if (sz != trg_size)
1047                         die("object %s inconsistent object length (%lu vs %lu)",
1048                             sha1_to_hex(trg_entry->sha1), sz, trg_size);
1049         }
1050         if (!src->data) {
1051                 src->data = read_sha1_file(src_entry->sha1, type, &sz);
1052                 if (sz != src_size)
1053                         die("object %s inconsistent object length (%lu vs %lu)",
1054                             sha1_to_hex(src_entry->sha1), sz, src_size);
1055         }
1056         if (!src->index) {
1057                 src->index = create_delta_index(src->data, src_size);
1058                 if (!src->index)
1059                         die("out of memory");
1060         }
1061
1062         delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1063         if (!delta_buf)
1064                 return 0;
1065
1066         trg_entry->delta = src_entry;
1067         trg_entry->delta_size = delta_size;
1068         trg_entry->depth = src_entry->depth + 1;
1069         free(delta_buf);
1070         return 1;
1071 }
1072
1073 static void progress_interval(int signum)
1074 {
1075         progress_update = 1;
1076 }
1077
1078 static void find_deltas(struct object_entry **list, int window, int depth)
1079 {
1080         int i, idx;
1081         unsigned int array_size = window * sizeof(struct unpacked);
1082         struct unpacked *array = xmalloc(array_size);
1083         unsigned processed = 0;
1084         unsigned last_percent = 999;
1085
1086         memset(array, 0, array_size);
1087         i = nr_objects;
1088         idx = 0;
1089         if (progress)
1090                 fprintf(stderr, "Deltifying %d objects.\n", nr_result);
1091
1092         while (--i >= 0) {
1093                 struct object_entry *entry = list[i];
1094                 struct unpacked *n = array + idx;
1095                 int j;
1096
1097                 if (!entry->preferred_base)
1098                         processed++;
1099
1100                 if (progress) {
1101                         unsigned percent = processed * 100 / nr_result;
1102                         if (percent != last_percent || progress_update) {
1103                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1104                                         percent, processed, nr_result);
1105                                 progress_update = 0;
1106                                 last_percent = percent;
1107                         }
1108                 }
1109
1110                 if (entry->delta)
1111                         /* This happens if we decided to reuse existing
1112                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1113                          */
1114                         continue;
1115
1116                 if (entry->size < 50)
1117                         continue;
1118                 free_delta_index(n->index);
1119                 n->index = NULL;
1120                 free(n->data);
1121                 n->data = NULL;
1122                 n->entry = entry;
1123
1124                 j = window;
1125                 while (--j > 0) {
1126                         unsigned int other_idx = idx + j;
1127                         struct unpacked *m;
1128                         if (other_idx >= window)
1129                                 other_idx -= window;
1130                         m = array + other_idx;
1131                         if (!m->entry)
1132                                 break;
1133                         if (try_delta(n, m, depth) < 0)
1134                                 break;
1135                 }
1136                 /* if we made n a delta, and if n is already at max
1137                  * depth, leaving it in the window is pointless.  we
1138                  * should evict it first.
1139                  */
1140                 if (entry->delta && depth <= entry->depth)
1141                         continue;
1142
1143                 idx++;
1144                 if (idx >= window)
1145                         idx = 0;
1146         }
1147
1148         if (progress)
1149                 fputc('\n', stderr);
1150
1151         for (i = 0; i < window; ++i) {
1152                 free_delta_index(array[i].index);
1153                 free(array[i].data);
1154         }
1155         free(array);
1156 }
1157
1158 static void prepare_pack(int window, int depth)
1159 {
1160         get_object_details();
1161         sorted_by_type = create_sorted_list(type_size_sort);
1162         if (window && depth)
1163                 find_deltas(sorted_by_type, window+1, depth);
1164 }
1165
1166 static int reuse_cached_pack(unsigned char *sha1, int pack_to_stdout)
1167 {
1168         static const char cache[] = "pack-cache/pack-%s.%s";
1169         char *cached_pack, *cached_idx;
1170         int ifd, ofd, ifd_ix = -1;
1171
1172         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1173         ifd = open(cached_pack, O_RDONLY);
1174         if (ifd < 0)
1175                 return 0;
1176
1177         if (!pack_to_stdout) {
1178                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1179                 ifd_ix = open(cached_idx, O_RDONLY);
1180                 if (ifd_ix < 0) {
1181                         close(ifd);
1182                         return 0;
1183                 }
1184         }
1185
1186         if (progress)
1187                 fprintf(stderr, "Reusing %d objects pack %s\n", nr_objects,
1188                         sha1_to_hex(sha1));
1189
1190         if (pack_to_stdout) {
1191                 if (copy_fd(ifd, 1))
1192                         exit(1);
1193                 close(ifd);
1194         }
1195         else {
1196                 char name[PATH_MAX];
1197                 snprintf(name, sizeof(name),
1198                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1199                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1200                 if (ofd < 0)
1201                         die("unable to open %s (%s)", name, strerror(errno));
1202                 if (copy_fd(ifd, ofd))
1203                         exit(1);
1204                 close(ifd);
1205
1206                 snprintf(name, sizeof(name),
1207                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1208                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1209                 if (ofd < 0)
1210                         die("unable to open %s (%s)", name, strerror(errno));
1211                 if (copy_fd(ifd_ix, ofd))
1212                         exit(1);
1213                 close(ifd_ix);
1214                 puts(sha1_to_hex(sha1));
1215         }
1216
1217         return 1;
1218 }
1219
1220 static void setup_progress_signal(void)
1221 {
1222         struct sigaction sa;
1223         struct itimerval v;
1224
1225         memset(&sa, 0, sizeof(sa));
1226         sa.sa_handler = progress_interval;
1227         sigemptyset(&sa.sa_mask);
1228         sa.sa_flags = SA_RESTART;
1229         sigaction(SIGALRM, &sa, NULL);
1230
1231         v.it_interval.tv_sec = 1;
1232         v.it_interval.tv_usec = 0;
1233         v.it_value = v.it_interval;
1234         setitimer(ITIMER_REAL, &v, NULL);
1235 }
1236
1237 static int git_pack_config(const char *k, const char *v)
1238 {
1239         if(!strcmp(k, "pack.window")) {
1240                 window = git_config_int(k, v);
1241                 return 0;
1242         }
1243         return git_default_config(k, v);
1244 }
1245
1246 int cmd_pack_objects(int argc, const char **argv, const char *prefix)
1247 {
1248         SHA_CTX ctx;
1249         char line[40 + 1 + PATH_MAX + 2];
1250         int depth = 10, pack_to_stdout = 0;
1251         struct object_entry **list;
1252         int num_preferred_base = 0;
1253         int i;
1254
1255         git_config(git_pack_config);
1256
1257         progress = isatty(2);
1258         for (i = 1; i < argc; i++) {
1259                 const char *arg = argv[i];
1260
1261                 if (*arg == '-') {
1262                         if (!strcmp("--non-empty", arg)) {
1263                                 non_empty = 1;
1264                                 continue;
1265                         }
1266                         if (!strcmp("--local", arg)) {
1267                                 local = 1;
1268                                 continue;
1269                         }
1270                         if (!strcmp("--progress", arg)) {
1271                                 progress = 1;
1272                                 continue;
1273                         }
1274                         if (!strcmp("--incremental", arg)) {
1275                                 incremental = 1;
1276                                 continue;
1277                         }
1278                         if (!strncmp("--window=", arg, 9)) {
1279                                 char *end;
1280                                 window = strtoul(arg+9, &end, 0);
1281                                 if (!arg[9] || *end)
1282                                         usage(pack_usage);
1283                                 continue;
1284                         }
1285                         if (!strncmp("--depth=", arg, 8)) {
1286                                 char *end;
1287                                 depth = strtoul(arg+8, &end, 0);
1288                                 if (!arg[8] || *end)
1289                                         usage(pack_usage);
1290                                 continue;
1291                         }
1292                         if (!strcmp("--progress", arg)) {
1293                                 progress = 1;
1294                                 continue;
1295                         }
1296                         if (!strcmp("-q", arg)) {
1297                                 progress = 0;
1298                                 continue;
1299                         }
1300                         if (!strcmp("--no-reuse-delta", arg)) {
1301                                 no_reuse_delta = 1;
1302                                 continue;
1303                         }
1304                         if (!strcmp("--stdout", arg)) {
1305                                 pack_to_stdout = 1;
1306                                 continue;
1307                         }
1308                         usage(pack_usage);
1309                 }
1310                 if (base_name)
1311                         usage(pack_usage);
1312                 base_name = arg;
1313         }
1314
1315         if (pack_to_stdout != !base_name)
1316                 usage(pack_usage);
1317
1318         prepare_packed_git();
1319
1320         if (progress) {
1321                 fprintf(stderr, "Generating pack...\n");
1322                 setup_progress_signal();
1323         }
1324
1325         for (;;) {
1326                 unsigned char sha1[20];
1327                 unsigned hash;
1328
1329                 if (!fgets(line, sizeof(line), stdin)) {
1330                         if (feof(stdin))
1331                                 break;
1332                         if (!ferror(stdin))
1333                                 die("fgets returned NULL, not EOF, not error!");
1334                         if (errno != EINTR)
1335                                 die("fgets: %s", strerror(errno));
1336                         clearerr(stdin);
1337                         continue;
1338                 }
1339
1340                 if (line[0] == '-') {
1341                         if (get_sha1_hex(line+1, sha1))
1342                                 die("expected edge sha1, got garbage:\n %s",
1343                                     line+1);
1344                         if (num_preferred_base++ < window)
1345                                 add_preferred_base(sha1);
1346                         continue;
1347                 }
1348                 if (get_sha1_hex(line, sha1))
1349                         die("expected sha1, got garbage:\n %s", line);
1350                 hash = name_hash(line+41);
1351                 add_preferred_base_object(line+41, hash);
1352                 add_object_entry(sha1, hash, 0);
1353         }
1354         if (progress)
1355                 fprintf(stderr, "Done counting %d objects.\n", nr_objects);
1356         sorted_by_sha = create_final_object_list();
1357         if (non_empty && !nr_result)
1358                 return 0;
1359
1360         SHA1_Init(&ctx);
1361         list = sorted_by_sha;
1362         for (i = 0; i < nr_result; i++) {
1363                 struct object_entry *entry = *list++;
1364                 SHA1_Update(&ctx, entry->sha1, 20);
1365         }
1366         SHA1_Final(object_list_sha1, &ctx);
1367         if (progress && (nr_objects != nr_result))
1368                 fprintf(stderr, "Result has %d objects.\n", nr_result);
1369
1370         if (reuse_cached_pack(object_list_sha1, pack_to_stdout))
1371                 ;
1372         else {
1373                 if (nr_result)
1374                         prepare_pack(window, depth);
1375                 if (progress && pack_to_stdout) {
1376                         /* the other end usually displays progress itself */
1377                         struct itimerval v = {{0,},};
1378                         setitimer(ITIMER_REAL, &v, NULL);
1379                         signal(SIGALRM, SIG_IGN );
1380                         progress_update = 0;
1381                 }
1382                 write_pack_file();
1383                 if (!pack_to_stdout) {
1384                         write_index_file();
1385                         puts(sha1_to_hex(object_list_sha1));
1386                 }
1387         }
1388         if (progress)
1389                 fprintf(stderr, "Total %d, written %d (delta %d), reused %d (delta %d)\n",
1390                         nr_result, written, written_delta, reused, reused_delta);
1391         return 0;
1392 }