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 "diff.h"
  13 #include "revision.h"
  14 #include "list-objects.h"
  15
  16 static const char pack_usage[] = "\
  17 git-pack-objects [{ -q | --progress | --all-progress }] \n\
  18         [--local] [--incremental] [--window=N] [--depth=N] \n\
  19         [--no-reuse-delta] [--delta-base-offset] [--non-empty] \n\
  20         [--revs [--unpacked | --all]*] [--reflog] [--stdout | base-name] \n\
  21         [<ref-list | <object-list]";
  22
  23 struct object_entry {
  24         unsigned char sha1[20];
  25         unsigned long size;     /* uncompressed size */
  26         off_t offset;   /* offset into the final pack file;
  27                                  * nonzero if already written.
  28                                  */
  29         unsigned int depth;     /* delta depth */
  30         unsigned int delta_limit;       /* base adjustment for in-pack delta */
  31         unsigned int hash;      /* name hint hash */
  32         enum object_type type;
  33         enum object_type in_pack_type;  /* could be delta */
  34         unsigned long delta_size;       /* delta data size (uncompressed) */
  35 #define in_pack_header_size delta_size  /* only when reusing pack data */
  36         struct object_entry *delta;     /* delta base object */
  37         struct packed_git *in_pack;     /* already in pack */
  38         off_t in_pack_offset;
  39         struct object_entry *delta_child; /* deltified objects who bases me */
  40         struct object_entry *delta_sibling; /* other deltified objects who
  41                                              * uses the same base as me
  42                                              */
  43         int preferred_base;     /* we do not pack this, but is encouraged to
  44                                  * be used as the base objectto delta huge
  45                                  * objects against.
  46                                  */
  47         uint32_t crc32;         /* crc of raw pack data for this object */
  48 };
  49
  50 /*
  51  * Objects we are going to pack are collected in objects array (dynamically
  52  * expanded).  nr_objects & nr_alloc controls this array.  They are stored
  53  * in the order we see -- typically rev-list --objects order that gives us
  54  * nice "minimum seek" order.
  55  *
  56  * sorted-by-sha ans sorted-by-type are arrays of pointers that point at
  57  * elements in the objects array.  The former is used to build the pack
  58  * index (lists object names in the ascending order to help offset lookup),
  59  * and the latter is used to group similar things together by try_delta()
  60  * heuristics.
  61  */
  62
  63 static unsigned char object_list_sha1[20];
  64 static int non_empty;
  65 static int no_reuse_delta;
  66 static int local;
  67 static int incremental;
  68 static int allow_ofs_delta;
  69
  70 static struct object_entry **sorted_by_sha, **sorted_by_type;
  71 static struct object_entry *objects;
  72 static uint32_t nr_objects, nr_alloc, nr_result;
  73 static const char *base_name;
  74 static unsigned char pack_file_sha1[20];
  75 static int progress = 1;
  76 static volatile sig_atomic_t progress_update;
  77 static int window = 10;
  78 static int pack_to_stdout;
  79 static int num_preferred_base;
  80
  81 /*
  82  * The object names in objects array are hashed with this hashtable,
  83  * to help looking up the entry by object name.  Binary search from
  84  * sorted_by_sha is also possible but this was easier to code and faster.
  85  * This hashtable is built after all the objects are seen.
  86  */
  87 static int *object_ix;
  88 static int object_ix_hashsz;
  89
  90 /*
  91  * Pack index for existing packs give us easy access to the offsets into
  92  * corresponding pack file where each object's data starts, but the entries
  93  * do not store the size of the compressed representation (uncompressed
  94  * size is easily available by examining the pack entry header).  It is
  95  * also rather expensive to find the sha1 for an object given its offset.
  96  *
  97  * We build a hashtable of existing packs (pack_revindex), and keep reverse
  98  * index here -- pack index file is sorted by object name mapping to offset;
  99  * this pack_revindex[].revindex array is a list of offset/index_nr pairs
 100  * ordered by offset, so if you know the offset of an object, next offset
 101  * is where its packed representation ends and the index_nr can be used to
 102  * get the object sha1 from the main index.
 103  */
 104 struct revindex_entry {
 105         off_t offset;
 106         unsigned int nr;
 107 };
 108 struct pack_revindex {
 109         struct packed_git *p;
 110         struct revindex_entry *revindex;
 111 };
 112 static struct  pack_revindex *pack_revindex;
 113 static int pack_revindex_hashsz;
 114
 115 /*
 116  * stats
 117  */
 118 static uint32_t written, written_delta;
 119 static uint32_t reused, reused_delta;
 120
 121 static int pack_revindex_ix(struct packed_git *p)
 122 {
 123         unsigned long ui = (unsigned long)p;
 124         int i;
 125
 126         ui = ui ^ (ui >> 16); /* defeat structure alignment */
 127         i = (int)(ui % pack_revindex_hashsz);
 128         while (pack_revindex[i].p) {
 129                 if (pack_revindex[i].p == p)
 130                         return i;
 131                 if (++i == pack_revindex_hashsz)
 132                         i = 0;
 133         }
 134         return -1 - i;
 135 }
 136
 137 static void prepare_pack_ix(void)
 138 {
 139         int num;
 140         struct packed_git *p;
 141         for (num = 0, p = packed_git; p; p = p->next)
 142                 num++;
 143         if (!num)
 144                 return;
 145         pack_revindex_hashsz = num * 11;
 146         pack_revindex = xcalloc(sizeof(*pack_revindex), pack_revindex_hashsz);
 147         for (p = packed_git; p; p = p->next) {
 148                 num = pack_revindex_ix(p);
 149                 num = - 1 - num;
 150                 pack_revindex[num].p = p;
 151         }
 152         /* revindex elements are lazily initialized */
 153 }
 154
 155 static int cmp_offset(const void *a_, const void *b_)
 156 {
 157         const struct revindex_entry *a = a_;
 158         const struct revindex_entry *b = b_;
 159         return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
 160 }
 161
 162 /*
 163  * Ordered list of offsets of objects in the pack.
 164  */
 165 static void prepare_pack_revindex(struct pack_revindex *rix)
 166 {
 167         struct packed_git *p = rix->p;
 168         int num_ent = p->num_objects;
 169         int i;
 170         const char *index = p->index_data;
 171
 172         index += 4 * 256;
 173         rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
 174         for (i = 0; i < num_ent; i++) {
 175                 uint32_t hl = *((uint32_t *)(index + 24 * i));
 176                 rix->revindex[i].offset = ntohl(hl);
 177                 rix->revindex[i].nr = i;
 178         }
 179         /* This knows the pack format -- the 20-byte trailer
 180          * follows immediately after the last object data.
 181          */
 182         rix->revindex[num_ent].offset = p->pack_size - 20;
 183         rix->revindex[num_ent].nr = -1;
 184         qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
 185 }
 186
 187 static struct revindex_entry * find_packed_object(struct packed_git *p,
 188                                                   off_t ofs)
 189 {
 190         int num;
 191         int lo, hi;
 192         struct pack_revindex *rix;
 193         struct revindex_entry *revindex;
 194         num = pack_revindex_ix(p);
 195         if (num < 0)
 196                 die("internal error: pack revindex uninitialized");
 197         rix = &pack_revindex[num];
 198         if (!rix->revindex)
 199                 prepare_pack_revindex(rix);
 200         revindex = rix->revindex;
 201         lo = 0;
 202         hi = p->num_objects + 1;
 203         do {
 204                 int mi = (lo + hi) / 2;
 205                 if (revindex[mi].offset == ofs) {
 206                         return revindex + mi;
 207                 }
 208                 else if (ofs < revindex[mi].offset)
 209                         hi = mi;
 210                 else
 211                         lo = mi + 1;
 212         } while (lo < hi);
 213         die("internal error: pack revindex corrupt");
 214 }
 215
 216 static off_t find_packed_object_size(struct packed_git *p, off_t ofs)
 217 {
 218         struct revindex_entry *entry = find_packed_object(p, ofs);
 219         return entry[1].offset - ofs;
 220 }
 221
 222 static const unsigned char *find_packed_object_name(struct packed_git *p,
 223                                                     off_t ofs)
 224 {
 225         struct revindex_entry *entry = find_packed_object(p, ofs);
 226         return nth_packed_object_sha1(p, entry->nr);
 227 }
 228
 229 static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
 230 {
 231         unsigned long othersize, delta_size;
 232         enum object_type type;
 233         void *otherbuf = read_sha1_file(entry->delta->sha1, &type, &othersize);
 234         void *delta_buf;
 235
 236         if (!otherbuf)
 237                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
 238         delta_buf = diff_delta(otherbuf, othersize,
 239                                buf, size, &delta_size, 0);
 240         if (!delta_buf || delta_size != entry->delta_size)
 241                 die("delta size changed");
 242         free(buf);
 243         free(otherbuf);
 244         return delta_buf;
 245 }
 246
 247 /*
 248  * The per-object header is a pretty dense thing, which is
 249  *  - first byte: low four bits are "size", then three bits of "type",
 250  *    and the high bit is "size continues".
 251  *  - each byte afterwards: low seven bits are size continuation,
 252  *    with the high bit being "size continues"
 253  */
 254 static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
 255 {
 256         int n = 1;
 257         unsigned char c;
 258
 259         if (type < OBJ_COMMIT || type > OBJ_REF_DELTA)
 260                 die("bad type %d", type);
 261
 262         c = (type << 4) | (size & 15);
 263         size >>= 4;
 264         while (size) {
 265                 *hdr++ = c | 0x80;
 266                 c = size & 0x7f;
 267                 size >>= 7;
 268                 n++;
 269         }
 270         *hdr = c;
 271         return n;
 272 }
 273
 274 /*
 275  * we are going to reuse the existing object data as is.  make
 276  * sure it is not corrupt.
 277  */
 278 static int check_pack_inflate(struct packed_git *p,
 279                 struct pack_window **w_curs,
 280                 off_t offset,
 281                 off_t len,
 282                 unsigned long expect)
 283 {
 284         z_stream stream;
 285         unsigned char fakebuf[4096], *in;
 286         int st;
 287
 288         memset(&stream, 0, sizeof(stream));
 289         inflateInit(&stream);
 290         do {
 291                 in = use_pack(p, w_curs, offset, &stream.avail_in);
 292                 stream.next_in = in;
 293                 stream.next_out = fakebuf;
 294                 stream.avail_out = sizeof(fakebuf);
 295                 st = inflate(&stream, Z_FINISH);
 296                 offset += stream.next_in - in;
 297         } while (st == Z_OK || st == Z_BUF_ERROR);
 298         inflateEnd(&stream);
 299         return (st == Z_STREAM_END &&
 300                 stream.total_out == expect &&
 301                 stream.total_in == len) ? 0 : -1;
 302 }
 303
 304 static void copy_pack_data(struct sha1file *f,
 305                 struct packed_git *p,
 306                 struct pack_window **w_curs,
 307                 off_t offset,
 308                 off_t len)
 309 {
 310         unsigned char *in;
 311         unsigned int avail;
 312
 313         while (len) {
 314                 in = use_pack(p, w_curs, offset, &avail);
 315                 if (avail > len)
 316                         avail = (unsigned int)len;
 317                 sha1write(f, in, avail);
 318                 offset += avail;
 319                 len -= avail;
 320         }
 321 }
 322
 323 static int check_loose_inflate(unsigned char *data, unsigned long len, unsigned long expect)
 324 {
 325         z_stream stream;
 326         unsigned char fakebuf[4096];
 327         int st;
 328
 329         memset(&stream, 0, sizeof(stream));
 330         stream.next_in = data;
 331         stream.avail_in = len;
 332         stream.next_out = fakebuf;
 333         stream.avail_out = sizeof(fakebuf);
 334         inflateInit(&stream);
 335
 336         while (1) {
 337                 st = inflate(&stream, Z_FINISH);
 338                 if (st == Z_STREAM_END || st == Z_OK) {
 339                         st = (stream.total_out == expect &&
 340                               stream.total_in == len) ? 0 : -1;
 341                         break;
 342                 }
 343                 if (st != Z_BUF_ERROR) {
 344                         st = -1;
 345                         break;
 346                 }
 347                 stream.next_out = fakebuf;
 348                 stream.avail_out = sizeof(fakebuf);
 349         }
 350         inflateEnd(&stream);
 351         return st;
 352 }
 353
 354 static int revalidate_loose_object(struct object_entry *entry,
 355                                    unsigned char *map,
 356                                    unsigned long mapsize)
 357 {
 358         /* we already know this is a loose object with new type header. */
 359         enum object_type type;
 360         unsigned long size, used;
 361
 362         if (pack_to_stdout)
 363                 return 0;
 364
 365         used = unpack_object_header_gently(map, mapsize, &type, &size);
 366         if (!used)
 367                 return -1;
 368         map += used;
 369         mapsize -= used;
 370         return check_loose_inflate(map, mapsize, size);
 371 }
 372
 373 static unsigned long write_object(struct sha1file *f,
 374                                   struct object_entry *entry)
 375 {
 376         unsigned long size;
 377         enum object_type type;
 378         void *buf;
 379         unsigned char header[10];
 380         unsigned hdrlen;
 381         off_t datalen;
 382         enum object_type obj_type;
 383         int to_reuse = 0;
 384
 385         if (!pack_to_stdout)
 386                 crc32_begin(f);
 387
 388         obj_type = entry->type;
 389         if (! entry->in_pack)
 390                 to_reuse = 0;   /* can't reuse what we don't have */
 391         else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
 392                 to_reuse = 1;   /* check_object() decided it for us */
 393         else if (obj_type != entry->in_pack_type)
 394                 to_reuse = 0;   /* pack has delta which is unusable */
 395         else if (entry->delta)
 396                 to_reuse = 0;   /* we want to pack afresh */
 397         else
 398                 to_reuse = 1;   /* we have it in-pack undeltified,
 399                                  * and we do not need to deltify it.
 400                                  */
 401
 402         if (!entry->in_pack && !entry->delta) {
 403                 unsigned char *map;
 404                 unsigned long mapsize;
 405                 map = map_sha1_file(entry->sha1, &mapsize);
 406                 if (map && !legacy_loose_object(map)) {
 407                         /* We can copy straight into the pack file */
 408                         if (revalidate_loose_object(entry, map, mapsize))
 409                                 die("corrupt loose object %s",
 410                                     sha1_to_hex(entry->sha1));
 411                         sha1write(f, map, mapsize);
 412                         munmap(map, mapsize);
 413                         written++;
 414                         reused++;
 415                         return mapsize;
 416                 }
 417                 if (map)
 418                         munmap(map, mapsize);
 419         }
 420
 421         if (!to_reuse) {
 422                 buf = read_sha1_file(entry->sha1, &type, &size);
 423                 if (!buf)
 424                         die("unable to read %s", sha1_to_hex(entry->sha1));
 425                 if (size != entry->size)
 426                         die("object %s size inconsistency (%lu vs %lu)",
 427                             sha1_to_hex(entry->sha1), size, entry->size);
 428                 if (entry->delta) {
 429                         buf = delta_against(buf, size, entry);
 430                         size = entry->delta_size;
 431                         obj_type = (allow_ofs_delta && entry->delta->offset) ?
 432                                 OBJ_OFS_DELTA : OBJ_REF_DELTA;
 433                 }
 434                 /*
 435                  * The object header is a byte of 'type' followed by zero or
 436                  * more bytes of length.
 437                  */
 438                 hdrlen = encode_header(obj_type, size, header);
 439                 sha1write(f, header, hdrlen);
 440
 441                 if (obj_type == OBJ_OFS_DELTA) {
 442                         /*
 443                          * Deltas with relative base contain an additional
 444                          * encoding of the relative offset for the delta
 445                          * base from this object's position in the pack.
 446                          */
 447                         off_t ofs = entry->offset - entry->delta->offset;
 448                         unsigned pos = sizeof(header) - 1;
 449                         header[pos] = ofs & 127;
 450                         while (ofs >>= 7)
 451                                 header[--pos] = 128 | (--ofs & 127);
 452                         sha1write(f, header + pos, sizeof(header) - pos);
 453                         hdrlen += sizeof(header) - pos;
 454                 } else if (obj_type == OBJ_REF_DELTA) {
 455                         /*
 456                          * Deltas with a base reference contain
 457                          * an additional 20 bytes for the base sha1.
 458                          */
 459                         sha1write(f, entry->delta->sha1, 20);
 460                         hdrlen += 20;
 461                 }
 462                 datalen = sha1write_compressed(f, buf, size);
 463                 free(buf);
 464         }
 465         else {
 466                 struct packed_git *p = entry->in_pack;
 467                 struct pack_window *w_curs = NULL;
 468                 off_t offset;
 469
 470                 if (entry->delta) {
 471                         obj_type = (allow_ofs_delta && entry->delta->offset) ?
 472                                 OBJ_OFS_DELTA : OBJ_REF_DELTA;
 473                         reused_delta++;
 474                 }
 475                 hdrlen = encode_header(obj_type, entry->size, header);
 476                 sha1write(f, header, hdrlen);
 477                 if (obj_type == OBJ_OFS_DELTA) {
 478                         off_t ofs = entry->offset - entry->delta->offset;
 479                         unsigned pos = sizeof(header) - 1;
 480                         header[pos] = ofs & 127;
 481                         while (ofs >>= 7)
 482                                 header[--pos] = 128 | (--ofs & 127);
 483                         sha1write(f, header + pos, sizeof(header) - pos);
 484                         hdrlen += sizeof(header) - pos;
 485                 } else if (obj_type == OBJ_REF_DELTA) {
 486                         sha1write(f, entry->delta->sha1, 20);
 487                         hdrlen += 20;
 488                 }
 489
 490                 offset = entry->in_pack_offset + entry->in_pack_header_size;
 491                 datalen = find_packed_object_size(p, entry->in_pack_offset)
 492                                 - entry->in_pack_header_size;
 493                 if (!pack_to_stdout && check_pack_inflate(p, &w_curs,
 494                                 offset, datalen, entry->size))
 495                         die("corrupt delta in pack %s", sha1_to_hex(entry->sha1));
 496                 copy_pack_data(f, p, &w_curs, offset, datalen);
 497                 unuse_pack(&w_curs);
 498                 reused++;
 499         }
 500         if (entry->delta)
 501                 written_delta++;
 502         written++;
 503         if (!pack_to_stdout)
 504                 entry->crc32 = crc32_end(f);
 505         return hdrlen + datalen;
 506 }
 507
 508 static off_t write_one(struct sha1file *f,
 509                                struct object_entry *e,
 510                                off_t offset)
 511 {
 512         unsigned long size;
 513
 514         /* offset is non zero if object is written already. */
 515         if (e->offset || e->preferred_base)
 516                 return offset;
 517
 518         /* if we are deltified, write out base object first. */
 519         if (e->delta)
 520                 offset = write_one(f, e->delta, offset);
 521
 522         e->offset = offset;
 523         size = write_object(f, e);
 524
 525         /* make sure off_t is sufficiently large not to wrap */
 526         if (offset > offset + size)
 527                 die("pack too large for current definition of off_t");
 528         return offset + size;
 529 }
 530
 531 static void write_pack_file(void)
 532 {
 533         uint32_t i;
 534         struct sha1file *f;
 535         off_t offset;
 536         struct pack_header hdr;
 537         unsigned last_percent = 999;
 538         int do_progress = progress;
 539
 540         if (!base_name) {
 541                 f = sha1fd(1, "<stdout>");
 542                 do_progress >>= 1;
 543         }
 544         else
 545                 f = sha1create("%s-%s.%s", base_name,
 546                                sha1_to_hex(object_list_sha1), "pack");
 547         if (do_progress)
 548                 fprintf(stderr, "Writing %u objects.\n", nr_result);
 549
 550         hdr.hdr_signature = htonl(PACK_SIGNATURE);
 551         hdr.hdr_version = htonl(PACK_VERSION);
 552         hdr.hdr_entries = htonl(nr_result);
 553         sha1write(f, &hdr, sizeof(hdr));
 554         offset = sizeof(hdr);
 555         if (!nr_result)
 556                 goto done;
 557         for (i = 0; i < nr_objects; i++) {
 558                 offset = write_one(f, objects + i, offset);
 559                 if (do_progress) {
 560                         unsigned percent = written * 100 / nr_result;
 561                         if (progress_update || percent != last_percent) {
 562                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 563                                         percent, written, nr_result);
 564                                 progress_update = 0;
 565                                 last_percent = percent;
 566                         }
 567                 }
 568         }
 569         if (do_progress)
 570                 fputc('\n', stderr);
 571  done:
 572         if (written != nr_result)
 573                 die("wrote %u objects while expecting %u", written, nr_result);
 574         sha1close(f, pack_file_sha1, 1);
 575 }
 576
 577 static void write_index_file(void)
 578 {
 579         uint32_t i;
 580         struct sha1file *f = sha1create("%s-%s.%s", base_name,
 581                                         sha1_to_hex(object_list_sha1), "idx");
 582         struct object_entry **list = sorted_by_sha;
 583         struct object_entry **last = list + nr_result;
 584         uint32_t array[256];
 585
 586         /*
 587          * Write the first-level table (the list is sorted,
 588          * but we use a 256-entry lookup to be able to avoid
 589          * having to do eight extra binary search iterations).
 590          */
 591         for (i = 0; i < 256; i++) {
 592                 struct object_entry **next = list;
 593                 while (next < last) {
 594                         struct object_entry *entry = *next;
 595                         if (entry->sha1[0] != i)
 596                                 break;
 597                         next++;
 598                 }
 599                 array[i] = htonl(next - sorted_by_sha);
 600                 list = next;
 601         }
 602         sha1write(f, array, 256 * 4);
 603
 604         /*
 605          * Write the actual SHA1 entries..
 606          */
 607         list = sorted_by_sha;
 608         for (i = 0; i < nr_result; i++) {
 609                 struct object_entry *entry = *list++;
 610                 uint32_t offset = htonl(entry->offset);
 611                 sha1write(f, &offset, 4);
 612                 sha1write(f, entry->sha1, 20);
 613         }
 614         sha1write(f, pack_file_sha1, 20);
 615         sha1close(f, NULL, 1);
 616 }
 617
 618 static int locate_object_entry_hash(const unsigned char *sha1)
 619 {
 620         int i;
 621         unsigned int ui;
 622         memcpy(&ui, sha1, sizeof(unsigned int));
 623         i = ui % object_ix_hashsz;
 624         while (0 < object_ix[i]) {
 625                 if (!hashcmp(sha1, objects[object_ix[i] - 1].sha1))
 626                         return i;
 627                 if (++i == object_ix_hashsz)
 628                         i = 0;
 629         }
 630         return -1 - i;
 631 }
 632
 633 static struct object_entry *locate_object_entry(const unsigned char *sha1)
 634 {
 635         int i;
 636
 637         if (!object_ix_hashsz)
 638                 return NULL;
 639
 640         i = locate_object_entry_hash(sha1);
 641         if (0 <= i)
 642                 return &objects[object_ix[i]-1];
 643         return NULL;
 644 }
 645
 646 static void rehash_objects(void)
 647 {
 648         uint32_t i;
 649         struct object_entry *oe;
 650
 651         object_ix_hashsz = nr_objects * 3;
 652         if (object_ix_hashsz < 1024)
 653                 object_ix_hashsz = 1024;
 654         object_ix = xrealloc(object_ix, sizeof(int) * object_ix_hashsz);
 655         memset(object_ix, 0, sizeof(int) * object_ix_hashsz);
 656         for (i = 0, oe = objects; i < nr_objects; i++, oe++) {
 657                 int ix = locate_object_entry_hash(oe->sha1);
 658                 if (0 <= ix)
 659                         continue;
 660                 ix = -1 - ix;
 661                 object_ix[ix] = i + 1;
 662         }
 663 }
 664
 665 static unsigned name_hash(const char *name)
 666 {
 667         unsigned char c;
 668         unsigned hash = 0;
 669
 670         /*
 671          * This effectively just creates a sortable number from the
 672          * last sixteen non-whitespace characters. Last characters
 673          * count "most", so things that end in ".c" sort together.
 674          */
 675         while ((c = *name++) != 0) {
 676                 if (isspace(c))
 677                         continue;
 678                 hash = (hash >> 2) + (c << 24);
 679         }
 680         return hash;
 681 }
 682
 683 static int add_object_entry(const unsigned char *sha1, unsigned hash, int exclude)
 684 {
 685         uint32_t idx = nr_objects;
 686         struct object_entry *entry;
 687         struct packed_git *p;
 688         off_t found_offset = 0;
 689         struct packed_git *found_pack = NULL;
 690         int ix, status = 0;
 691
 692         if (!exclude) {
 693                 for (p = packed_git; p; p = p->next) {
 694                         off_t offset = find_pack_entry_one(sha1, p);
 695                         if (offset) {
 696                                 if (incremental)
 697                                         return 0;
 698                                 if (local && !p->pack_local)
 699                                         return 0;
 700                                 if (!found_pack) {
 701                                         found_offset = offset;
 702                                         found_pack = p;
 703                                 }
 704                         }
 705                 }
 706         }
 707         if ((entry = locate_object_entry(sha1)) != NULL)
 708                 goto already_added;
 709
 710         if (idx >= nr_alloc) {
 711                 nr_alloc = (idx + 1024) * 3 / 2;
 712                 objects = xrealloc(objects, nr_alloc * sizeof(*entry));
 713         }
 714         entry = objects + idx;
 715         nr_objects = idx + 1;
 716         memset(entry, 0, sizeof(*entry));
 717         hashcpy(entry->sha1, sha1);
 718         entry->hash = hash;
 719
 720         if (object_ix_hashsz * 3 <= nr_objects * 4)
 721                 rehash_objects();
 722         else {
 723                 ix = locate_object_entry_hash(entry->sha1);
 724                 if (0 <= ix)
 725                         die("internal error in object hashing.");
 726                 object_ix[-1 - ix] = idx + 1;
 727         }
 728         status = 1;
 729
 730  already_added:
 731         if (progress_update) {
 732                 fprintf(stderr, "Counting objects...%u\r", nr_objects);
 733                 progress_update = 0;
 734         }
 735         if (exclude)
 736                 entry->preferred_base = 1;
 737         else {
 738                 if (found_pack) {
 739                         entry->in_pack = found_pack;
 740                         entry->in_pack_offset = found_offset;
 741                 }
 742         }
 743         return status;
 744 }
 745
 746 struct pbase_tree_cache {
 747         unsigned char sha1[20];
 748         int ref;
 749         int temporary;
 750         void *tree_data;
 751         unsigned long tree_size;
 752 };
 753
 754 static struct pbase_tree_cache *(pbase_tree_cache[256]);
 755 static int pbase_tree_cache_ix(const unsigned char *sha1)
 756 {
 757         return sha1[0] % ARRAY_SIZE(pbase_tree_cache);
 758 }
 759 static int pbase_tree_cache_ix_incr(int ix)
 760 {
 761         return (ix+1) % ARRAY_SIZE(pbase_tree_cache);
 762 }
 763
 764 static struct pbase_tree {
 765         struct pbase_tree *next;
 766         /* This is a phony "cache" entry; we are not
 767          * going to evict it nor find it through _get()
 768          * mechanism -- this is for the toplevel node that
 769          * would almost always change with any commit.
 770          */
 771         struct pbase_tree_cache pcache;
 772 } *pbase_tree;
 773
 774 static struct pbase_tree_cache *pbase_tree_get(const unsigned char *sha1)
 775 {
 776         struct pbase_tree_cache *ent, *nent;
 777         void *data;
 778         unsigned long size;
 779         enum object_type type;
 780         int neigh;
 781         int my_ix = pbase_tree_cache_ix(sha1);
 782         int available_ix = -1;
 783
 784         /* pbase-tree-cache acts as a limited hashtable.
 785          * your object will be found at your index or within a few
 786          * slots after that slot if it is cached.
 787          */
 788         for (neigh = 0; neigh < 8; neigh++) {
 789                 ent = pbase_tree_cache[my_ix];
 790                 if (ent && !hashcmp(ent->sha1, sha1)) {
 791                         ent->ref++;
 792                         return ent;
 793                 }
 794                 else if (((available_ix < 0) && (!ent || !ent->ref)) ||
 795                          ((0 <= available_ix) &&
 796                           (!ent && pbase_tree_cache[available_ix])))
 797                         available_ix = my_ix;
 798                 if (!ent)
 799                         break;
 800                 my_ix = pbase_tree_cache_ix_incr(my_ix);
 801         }
 802
 803         /* Did not find one.  Either we got a bogus request or
 804          * we need to read and perhaps cache.
 805          */
 806         data = read_sha1_file(sha1, &type, &size);
 807         if (!data)
 808                 return NULL;
 809         if (type != OBJ_TREE) {
 810                 free(data);
 811                 return NULL;
 812         }
 813
 814         /* We need to either cache or return a throwaway copy */
 815
 816         if (available_ix < 0)
 817                 ent = NULL;
 818         else {
 819                 ent = pbase_tree_cache[available_ix];
 820                 my_ix = available_ix;
 821         }
 822
 823         if (!ent) {
 824                 nent = xmalloc(sizeof(*nent));
 825                 nent->temporary = (available_ix < 0);
 826         }
 827         else {
 828                 /* evict and reuse */
 829                 free(ent->tree_data);
 830                 nent = ent;
 831         }
 832         hashcpy(nent->sha1, sha1);
 833         nent->tree_data = data;
 834         nent->tree_size = size;
 835         nent->ref = 1;
 836         if (!nent->temporary)
 837                 pbase_tree_cache[my_ix] = nent;
 838         return nent;
 839 }
 840
 841 static void pbase_tree_put(struct pbase_tree_cache *cache)
 842 {
 843         if (!cache->temporary) {
 844                 cache->ref--;
 845                 return;
 846         }
 847         free(cache->tree_data);
 848         free(cache);
 849 }
 850
 851 static int name_cmp_len(const char *name)
 852 {
 853         int i;
 854         for (i = 0; name[i] && name[i] != '\n' && name[i] != '/'; i++)
 855                 ;
 856         return i;
 857 }
 858
 859 static void add_pbase_object(struct tree_desc *tree,
 860                              const char *name,
 861                              int cmplen,
 862                              const char *fullname)
 863 {
 864         struct name_entry entry;
 865
 866         while (tree_entry(tree,&entry)) {
 867                 unsigned long size;
 868                 enum object_type type;
 869
 870                 if (tree_entry_len(entry.path, entry.sha1) != cmplen ||
 871                     memcmp(entry.path, name, cmplen) ||
 872                     !has_sha1_file(entry.sha1) ||
 873                     (type = sha1_object_info(entry.sha1, &size)) < 0)
 874                         continue;
 875                 if (name[cmplen] != '/') {
 876                         unsigned hash = name_hash(fullname);
 877                         add_object_entry(entry.sha1, hash, 1);
 878                         return;
 879                 }
 880                 if (type == OBJ_TREE) {
 881                         struct tree_desc sub;
 882                         struct pbase_tree_cache *tree;
 883                         const char *down = name+cmplen+1;
 884                         int downlen = name_cmp_len(down);
 885
 886                         tree = pbase_tree_get(entry.sha1);
 887                         if (!tree)
 888                                 return;
 889                         init_tree_desc(&sub, tree->tree_data, tree->tree_size);
 890
 891                         add_pbase_object(&sub, down, downlen, fullname);
 892                         pbase_tree_put(tree);
 893                 }
 894         }
 895 }
 896
 897 static unsigned *done_pbase_paths;
 898 static int done_pbase_paths_num;
 899 static int done_pbase_paths_alloc;
 900 static int done_pbase_path_pos(unsigned hash)
 901 {
 902         int lo = 0;
 903         int hi = done_pbase_paths_num;
 904         while (lo < hi) {
 905                 int mi = (hi + lo) / 2;
 906                 if (done_pbase_paths[mi] == hash)
 907                         return mi;
 908                 if (done_pbase_paths[mi] < hash)
 909                         hi = mi;
 910                 else
 911                         lo = mi + 1;
 912         }
 913         return -lo-1;
 914 }
 915
 916 static int check_pbase_path(unsigned hash)
 917 {
 918         int pos = (!done_pbase_paths) ? -1 : done_pbase_path_pos(hash);
 919         if (0 <= pos)
 920                 return 1;
 921         pos = -pos - 1;
 922         if (done_pbase_paths_alloc <= done_pbase_paths_num) {
 923                 done_pbase_paths_alloc = alloc_nr(done_pbase_paths_alloc);
 924                 done_pbase_paths = xrealloc(done_pbase_paths,
 925                                             done_pbase_paths_alloc *
 926                                             sizeof(unsigned));
 927         }
 928         done_pbase_paths_num++;
 929         if (pos < done_pbase_paths_num)
 930                 memmove(done_pbase_paths + pos + 1,
 931                         done_pbase_paths + pos,
 932                         (done_pbase_paths_num - pos - 1) * sizeof(unsigned));
 933         done_pbase_paths[pos] = hash;
 934         return 0;
 935 }
 936
 937 static void add_preferred_base_object(const char *name, unsigned hash)
 938 {
 939         struct pbase_tree *it;
 940         int cmplen = name_cmp_len(name);
 941
 942         if (check_pbase_path(hash))
 943                 return;
 944
 945         for (it = pbase_tree; it; it = it->next) {
 946                 if (cmplen == 0) {
 947                         hash = name_hash("");
 948                         add_object_entry(it->pcache.sha1, hash, 1);
 949                 }
 950                 else {
 951                         struct tree_desc tree;
 952                         init_tree_desc(&tree, it->pcache.tree_data, it->pcache.tree_size);
 953                         add_pbase_object(&tree, name, cmplen, name);
 954                 }
 955         }
 956 }
 957
 958 static void add_preferred_base(unsigned char *sha1)
 959 {
 960         struct pbase_tree *it;
 961         void *data;
 962         unsigned long size;
 963         unsigned char tree_sha1[20];
 964
 965         if (window <= num_preferred_base++)
 966                 return;
 967
 968         data = read_object_with_reference(sha1, tree_type, &size, tree_sha1);
 969         if (!data)
 970                 return;
 971
 972         for (it = pbase_tree; it; it = it->next) {
 973                 if (!hashcmp(it->pcache.sha1, tree_sha1)) {
 974                         free(data);
 975                         return;
 976                 }
 977         }
 978
 979         it = xcalloc(1, sizeof(*it));
 980         it->next = pbase_tree;
 981         pbase_tree = it;
 982
 983         hashcpy(it->pcache.sha1, tree_sha1);
 984         it->pcache.tree_data = data;
 985         it->pcache.tree_size = size;
 986 }
 987
 988 static void check_object(struct object_entry *entry)
 989 {
 990         if (entry->in_pack && !entry->preferred_base) {
 991                 struct packed_git *p = entry->in_pack;
 992                 struct pack_window *w_curs = NULL;
 993                 unsigned long size, used;
 994                 unsigned int avail;
 995                 unsigned char *buf;
 996                 struct object_entry *base_entry = NULL;
 997
 998                 buf = use_pack(p, &w_curs, entry->in_pack_offset, &avail);
 999
1000                 /* We want in_pack_type even if we do not reuse delta.
1001                  * There is no point not reusing non-delta representations.
1002                  */
1003                 used = unpack_object_header_gently(buf, avail,
1004                                                    &entry->in_pack_type, &size);
1005
1006                 /* Check if it is delta, and the base is also an object
1007                  * we are going to pack.  If so we will reuse the existing
1008                  * delta.
1009                  */
1010                 if (!no_reuse_delta) {
1011                         unsigned char c;
1012                         const unsigned char *base_name;
1013                         off_t ofs;
1014                         unsigned long used_0;
1015                         /* there is at least 20 bytes left in the pack */
1016                         switch (entry->in_pack_type) {
1017                         case OBJ_REF_DELTA:
1018                                 base_name = use_pack(p, &w_curs,
1019                                         entry->in_pack_offset + used, NULL);
1020                                 used += 20;
1021                                 break;
1022                         case OBJ_OFS_DELTA:
1023                                 buf = use_pack(p, &w_curs,
1024                                         entry->in_pack_offset + used, NULL);
1025                                 used_0 = 0;
1026                                 c = buf[used_0++];
1027                                 ofs = c & 127;
1028                                 while (c & 128) {
1029                                         ofs += 1;
1030                                         if (!ofs || MSB(ofs, 7))
1031                                                 die("delta base offset overflow in pack for %s",
1032                                                     sha1_to_hex(entry->sha1));
1033                                         c = buf[used_0++];
1034                                         ofs = (ofs << 7) + (c & 127);
1035                                 }
1036                                 if (ofs >= entry->in_pack_offset)
1037                                         die("delta base offset out of bound for %s",
1038                                             sha1_to_hex(entry->sha1));
1039                                 ofs = entry->in_pack_offset - ofs;
1040                                 base_name = find_packed_object_name(p, ofs);
1041                                 used += used_0;
1042                                 break;
1043                         default:
1044                                 base_name = NULL;
1045                         }
1046                         if (base_name)
1047                                 base_entry = locate_object_entry(base_name);
1048                 }
1049                 unuse_pack(&w_curs);
1050                 entry->in_pack_header_size = used;
1051
1052                 if (base_entry) {
1053
1054                         /* Depth value does not matter - find_deltas()
1055                          * will never consider reused delta as the
1056                          * base object to deltify other objects
1057                          * against, in order to avoid circular deltas.
1058                          */
1059
1060                         /* uncompressed size of the delta data */
1061                         entry->size = size;
1062                         entry->delta = base_entry;
1063                         entry->type = entry->in_pack_type;
1064
1065                         entry->delta_sibling = base_entry->delta_child;
1066                         base_entry->delta_child = entry;
1067
1068                         return;
1069                 }
1070                 /* Otherwise we would do the usual */
1071         }
1072
1073         entry->type = sha1_object_info(entry->sha1, &entry->size);
1074         if (entry->type < 0)
1075                 die("unable to get type of object %s",
1076                     sha1_to_hex(entry->sha1));
1077 }
1078
1079 static unsigned int check_delta_limit(struct object_entry *me, unsigned int n)
1080 {
1081         struct object_entry *child = me->delta_child;
1082         unsigned int m = n;
1083         while (child) {
1084                 unsigned int c = check_delta_limit(child, n + 1);
1085                 if (m < c)
1086                         m = c;
1087                 child = child->delta_sibling;
1088         }
1089         return m;
1090 }
1091
1092 static void get_object_details(void)
1093 {
1094         uint32_t i;
1095         struct object_entry *entry;
1096
1097         prepare_pack_ix();
1098         for (i = 0, entry = objects; i < nr_objects; i++, entry++)
1099                 check_object(entry);
1100
1101         if (nr_objects == nr_result) {
1102                 /*
1103                  * Depth of objects that depend on the entry -- this
1104                  * is subtracted from depth-max to break too deep
1105                  * delta chain because of delta data reusing.
1106                  * However, we loosen this restriction when we know we
1107                  * are creating a thin pack -- it will have to be
1108                  * expanded on the other end anyway, so do not
1109                  * artificially cut the delta chain and let it go as
1110                  * deep as it wants.
1111                  */
1112                 for (i = 0, entry = objects; i < nr_objects; i++, entry++)
1113                         if (!entry->delta && entry->delta_child)
1114                                 entry->delta_limit =
1115                                         check_delta_limit(entry, 1);
1116         }
1117 }
1118
1119 typedef int (*entry_sort_t)(const struct object_entry *, const struct object_entry *);
1120
1121 static entry_sort_t current_sort;
1122
1123 static int sort_comparator(const void *_a, const void *_b)
1124 {
1125         struct object_entry *a = *(struct object_entry **)_a;
1126         struct object_entry *b = *(struct object_entry **)_b;
1127         return current_sort(a,b);
1128 }
1129
1130 static struct object_entry **create_sorted_list(entry_sort_t sort)
1131 {
1132         struct object_entry **list = xmalloc(nr_objects * sizeof(struct object_entry *));
1133         uint32_t i;
1134
1135         for (i = 0; i < nr_objects; i++)
1136                 list[i] = objects + i;
1137         current_sort = sort;
1138         qsort(list, nr_objects, sizeof(struct object_entry *), sort_comparator);
1139         return list;
1140 }
1141
1142 static int sha1_sort(const struct object_entry *a, const struct object_entry *b)
1143 {
1144         return hashcmp(a->sha1, b->sha1);
1145 }
1146
1147 static struct object_entry **create_final_object_list(void)
1148 {
1149         struct object_entry **list;
1150         uint32_t i, j;
1151
1152         for (i = nr_result = 0; i < nr_objects; i++)
1153                 if (!objects[i].preferred_base)
1154                         nr_result++;
1155         list = xmalloc(nr_result * sizeof(struct object_entry *));
1156         for (i = j = 0; i < nr_objects; i++) {
1157                 if (!objects[i].preferred_base)
1158                         list[j++] = objects + i;
1159         }
1160         current_sort = sha1_sort;
1161         qsort(list, nr_result, sizeof(struct object_entry *), sort_comparator);
1162         return list;
1163 }
1164
1165 static int type_size_sort(const struct object_entry *a, const struct object_entry *b)
1166 {
1167         if (a->type < b->type)
1168                 return -1;
1169         if (a->type > b->type)
1170                 return 1;
1171         if (a->hash < b->hash)
1172                 return -1;
1173         if (a->hash > b->hash)
1174                 return 1;
1175         if (a->preferred_base < b->preferred_base)
1176                 return -1;
1177         if (a->preferred_base > b->preferred_base)
1178                 return 1;
1179         if (a->size < b->size)
1180                 return -1;
1181         if (a->size > b->size)
1182                 return 1;
1183         return a < b ? -1 : (a > b);
1184 }
1185
1186 struct unpacked {
1187         struct object_entry *entry;
1188         void *data;
1189         struct delta_index *index;
1190 };
1191
1192 /*
1193  * We search for deltas _backwards_ in a list sorted by type and
1194  * by size, so that we see progressively smaller and smaller files.
1195  * That's because we prefer deltas to be from the bigger file
1196  * to the smaller - deletes are potentially cheaper, but perhaps
1197  * more importantly, the bigger file is likely the more recent
1198  * one.
1199  */
1200 static int try_delta(struct unpacked *trg, struct unpacked *src,
1201                      unsigned max_depth)
1202 {
1203         struct object_entry *trg_entry = trg->entry;
1204         struct object_entry *src_entry = src->entry;
1205         unsigned long trg_size, src_size, delta_size, sizediff, max_size, sz;
1206         enum object_type type;
1207         void *delta_buf;
1208
1209         /* Don't bother doing diffs between different types */
1210         if (trg_entry->type != src_entry->type)
1211                 return -1;
1212
1213         /* We do not compute delta to *create* objects we are not
1214          * going to pack.
1215          */
1216         if (trg_entry->preferred_base)
1217                 return -1;
1218
1219         /*
1220          * We do not bother to try a delta that we discarded
1221          * on an earlier try, but only when reusing delta data.
1222          */
1223         if (!no_reuse_delta && trg_entry->in_pack &&
1224             trg_entry->in_pack == src_entry->in_pack &&
1225             trg_entry->in_pack_type != OBJ_REF_DELTA &&
1226             trg_entry->in_pack_type != OBJ_OFS_DELTA)
1227                 return 0;
1228
1229         /*
1230          * If the current object is at pack edge, take the depth the
1231          * objects that depend on the current object into account --
1232          * otherwise they would become too deep.
1233          */
1234         if (trg_entry->delta_child) {
1235                 if (max_depth <= trg_entry->delta_limit)
1236                         return 0;
1237                 max_depth -= trg_entry->delta_limit;
1238         }
1239         if (src_entry->depth >= max_depth)
1240                 return 0;
1241
1242         /* Now some size filtering heuristics. */
1243         trg_size = trg_entry->size;
1244         max_size = trg_size/2 - 20;
1245         max_size = max_size * (max_depth - src_entry->depth) / max_depth;
1246         if (max_size == 0)
1247                 return 0;
1248         if (trg_entry->delta && trg_entry->delta_size <= max_size)
1249                 max_size = trg_entry->delta_size-1;
1250         src_size = src_entry->size;
1251         sizediff = src_size < trg_size ? trg_size - src_size : 0;
1252         if (sizediff >= max_size)
1253                 return 0;
1254
1255         /* Load data if not already done */
1256         if (!trg->data) {
1257                 trg->data = read_sha1_file(trg_entry->sha1, &type, &sz);
1258                 if (sz != trg_size)
1259                         die("object %s inconsistent object length (%lu vs %lu)",
1260                             sha1_to_hex(trg_entry->sha1), sz, trg_size);
1261         }
1262         if (!src->data) {
1263                 src->data = read_sha1_file(src_entry->sha1, &type, &sz);
1264                 if (sz != src_size)
1265                         die("object %s inconsistent object length (%lu vs %lu)",
1266                             sha1_to_hex(src_entry->sha1), sz, src_size);
1267         }
1268         if (!src->index) {
1269                 src->index = create_delta_index(src->data, src_size);
1270                 if (!src->index)
1271                         die("out of memory");
1272         }
1273
1274         delta_buf = create_delta(src->index, trg->data, trg_size, &delta_size, max_size);
1275         if (!delta_buf)
1276                 return 0;
1277
1278         trg_entry->delta = src_entry;
1279         trg_entry->delta_size = delta_size;
1280         trg_entry->depth = src_entry->depth + 1;
1281         free(delta_buf);
1282         return 1;
1283 }
1284
1285 static void progress_interval(int signum)
1286 {
1287         progress_update = 1;
1288 }
1289
1290 static void find_deltas(struct object_entry **list, int window, int depth)
1291 {
1292         uint32_t i = nr_objects, idx = 0, processed = 0;
1293         unsigned int array_size = window * sizeof(struct unpacked);
1294         struct unpacked *array;
1295         unsigned last_percent = 999;
1296
1297         if (!nr_objects)
1298                 return;
1299         array = xmalloc(array_size);
1300         memset(array, 0, array_size);
1301         if (progress)
1302                 fprintf(stderr, "Deltifying %u objects.\n", nr_result);
1303
1304         do {
1305                 struct object_entry *entry = list[--i];
1306                 struct unpacked *n = array + idx;
1307                 int j;
1308
1309                 if (!entry->preferred_base)
1310                         processed++;
1311
1312                 if (progress) {
1313                         unsigned percent = processed * 100 / nr_result;
1314                         if (percent != last_percent || progress_update) {
1315                                 fprintf(stderr, "%4u%% (%u/%u) done\r",
1316                                         percent, processed, nr_result);
1317                                 progress_update = 0;
1318                                 last_percent = percent;
1319                         }
1320                 }
1321
1322                 if (entry->delta)
1323                         /* This happens if we decided to reuse existing
1324                          * delta from a pack.  "!no_reuse_delta &&" is implied.
1325                          */
1326                         continue;
1327
1328                 if (entry->size < 50)
1329                         continue;
1330                 free_delta_index(n->index);
1331                 n->index = NULL;
1332                 free(n->data);
1333                 n->data = NULL;
1334                 n->entry = entry;
1335
1336                 j = window;
1337                 while (--j > 0) {
1338                         uint32_t other_idx = idx + j;
1339                         struct unpacked *m;
1340                         if (other_idx >= window)
1341                                 other_idx -= window;
1342                         m = array + other_idx;
1343                         if (!m->entry)
1344                                 break;
1345                         if (try_delta(n, m, depth) < 0)
1346                                 break;
1347                 }
1348                 /* if we made n a delta, and if n is already at max
1349                  * depth, leaving it in the window is pointless.  we
1350                  * should evict it first.
1351                  */
1352                 if (entry->delta && depth <= entry->depth)
1353                         continue;
1354
1355                 idx++;
1356                 if (idx >= window)
1357                         idx = 0;
1358         } while (i > 0);
1359
1360         if (progress)
1361                 fputc('\n', stderr);
1362
1363         for (i = 0; i < window; ++i) {
1364                 free_delta_index(array[i].index);
1365                 free(array[i].data);
1366         }
1367         free(array);
1368 }
1369
1370 static void prepare_pack(int window, int depth)
1371 {
1372         get_object_details();
1373         sorted_by_type = create_sorted_list(type_size_sort);
1374         if (window && depth)
1375                 find_deltas(sorted_by_type, window+1, depth);
1376 }
1377
1378 static int reuse_cached_pack(unsigned char *sha1)
1379 {
1380         static const char cache[] = "pack-cache/pack-%s.%s";
1381         char *cached_pack, *cached_idx;
1382         int ifd, ofd, ifd_ix = -1;
1383
1384         cached_pack = git_path(cache, sha1_to_hex(sha1), "pack");
1385         ifd = open(cached_pack, O_RDONLY);
1386         if (ifd < 0)
1387                 return 0;
1388
1389         if (!pack_to_stdout) {
1390                 cached_idx = git_path(cache, sha1_to_hex(sha1), "idx");
1391                 ifd_ix = open(cached_idx, O_RDONLY);
1392                 if (ifd_ix < 0) {
1393                         close(ifd);
1394                         return 0;
1395                 }
1396         }
1397
1398         if (progress)
1399                 fprintf(stderr, "Reusing %u objects pack %s\n", nr_objects,
1400                         sha1_to_hex(sha1));
1401
1402         if (pack_to_stdout) {
1403                 if (copy_fd(ifd, 1))
1404                         exit(1);
1405                 close(ifd);
1406         }
1407         else {
1408                 char name[PATH_MAX];
1409                 snprintf(name, sizeof(name),
1410                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "pack");
1411                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1412                 if (ofd < 0)
1413                         die("unable to open %s (%s)", name, strerror(errno));
1414                 if (copy_fd(ifd, ofd))
1415                         exit(1);
1416                 close(ifd);
1417
1418                 snprintf(name, sizeof(name),
1419                          "%s-%s.%s", base_name, sha1_to_hex(sha1), "idx");
1420                 ofd = open(name, O_CREAT | O_EXCL | O_WRONLY, 0666);
1421                 if (ofd < 0)
1422                         die("unable to open %s (%s)", name, strerror(errno));
1423                 if (copy_fd(ifd_ix, ofd))
1424                         exit(1);
1425                 close(ifd_ix);
1426                 puts(sha1_to_hex(sha1));
1427         }
1428
1429         return 1;
1430 }
1431
1432 static void setup_progress_signal(void)
1433 {
1434         struct sigaction sa;
1435         struct itimerval v;
1436
1437         memset(&sa, 0, sizeof(sa));
1438         sa.sa_handler = progress_interval;
1439         sigemptyset(&sa.sa_mask);
1440         sa.sa_flags = SA_RESTART;
1441         sigaction(SIGALRM, &sa, NULL);
1442
1443         v.it_interval.tv_sec = 1;
1444         v.it_interval.tv_usec = 0;
1445         v.it_value = v.it_interval;
1446         setitimer(ITIMER_REAL, &v, NULL);
1447 }
1448
1449 static int git_pack_config(const char *k, const char *v)
1450 {
1451         if(!strcmp(k, "pack.window")) {
1452                 window = git_config_int(k, v);
1453                 return 0;
1454         }
1455         return git_default_config(k, v);
1456 }
1457
1458 static void read_object_list_from_stdin(void)
1459 {
1460         char line[40 + 1 + PATH_MAX + 2];
1461         unsigned char sha1[20];
1462         unsigned hash;
1463
1464         for (;;) {
1465                 if (!fgets(line, sizeof(line), stdin)) {
1466                         if (feof(stdin))
1467                                 break;
1468                         if (!ferror(stdin))
1469                                 die("fgets returned NULL, not EOF, not error!");
1470                         if (errno != EINTR)
1471                                 die("fgets: %s", strerror(errno));
1472                         clearerr(stdin);
1473                         continue;
1474                 }
1475                 if (line[0] == '-') {
1476                         if (get_sha1_hex(line+1, sha1))
1477                                 die("expected edge sha1, got garbage:\n %s",
1478                                     line);
1479                         add_preferred_base(sha1);
1480                         continue;
1481                 }
1482                 if (get_sha1_hex(line, sha1))
1483                         die("expected sha1, got garbage:\n %s", line);
1484
1485                 hash = name_hash(line+41);
1486                 add_preferred_base_object(line+41, hash);
1487                 add_object_entry(sha1, hash, 0);
1488         }
1489 }
1490
1491 static void show_commit(struct commit *commit)
1492 {
1493         unsigned hash = name_hash("");
1494         add_preferred_base_object("", hash);
1495         add_object_entry(commit->object.sha1, hash, 0);
1496 }
1497
1498 static void show_object(struct object_array_entry *p)
1499 {
1500         unsigned hash = name_hash(p->name);
1501         add_preferred_base_object(p->name, hash);
1502         add_object_entry(p->item->sha1, hash, 0);
1503 }
1504
1505 static void show_edge(struct commit *commit)
1506 {
1507         add_preferred_base(commit->object.sha1);
1508 }
1509
1510 static void get_object_list(int ac, const char **av)
1511 {
1512         struct rev_info revs;
1513         char line[1000];
1514         int flags = 0;
1515
1516         init_revisions(&revs, NULL);
1517         save_commit_buffer = 0;
1518         track_object_refs = 0;
1519         setup_revisions(ac, av, &revs, NULL);
1520
1521         while (fgets(line, sizeof(line), stdin) != NULL) {
1522                 int len = strlen(line);
1523                 if (line[len - 1] == '\n')
1524                         line[--len] = 0;
1525                 if (!len)
1526                         break;
1527                 if (*line == '-') {
1528                         if (!strcmp(line, "--not")) {
1529                                 flags ^= UNINTERESTING;
1530                                 continue;
1531                         }
1532                         die("not a rev '%s'", line);
1533                 }
1534                 if (handle_revision_arg(line, &revs, flags, 1))
1535                         die("bad revision '%s'", line);
1536         }
1537
1538         prepare_revision_walk(&revs);
1539         mark_edges_uninteresting(revs.commits, &revs, show_edge);
1540         traverse_commit_list(&revs, show_commit, show_object);
1541 }
1542
1543 int cmd_pack_objects(int argc, const char **argv, const char *prefix)
1544 {
1545         SHA_CTX ctx;
1546         int depth = 10;
1547         struct object_entry **list;
1548         int use_internal_rev_list = 0;
1549         int thin = 0;
1550         uint32_t i;
1551         const char **rp_av;
1552         int rp_ac_alloc = 64;
1553         int rp_ac;
1554
1555         rp_av = xcalloc(rp_ac_alloc, sizeof(*rp_av));
1556
1557         rp_av[0] = "pack-objects";
1558         rp_av[1] = "--objects"; /* --thin will make it --objects-edge */
1559         rp_ac = 2;
1560
1561         git_config(git_pack_config);
1562
1563         progress = isatty(2);
1564         for (i = 1; i < argc; i++) {
1565                 const char *arg = argv[i];
1566
1567                 if (*arg != '-')
1568                         break;
1569
1570                 if (!strcmp("--non-empty", arg)) {
1571                         non_empty = 1;
1572                         continue;
1573                 }
1574                 if (!strcmp("--local", arg)) {
1575                         local = 1;
1576                         continue;
1577                 }
1578                 if (!strcmp("--incremental", arg)) {
1579                         incremental = 1;
1580                         continue;
1581                 }
1582                 if (!prefixcmp(arg, "--window=")) {
1583                         char *end;
1584                         window = strtoul(arg+9, &end, 0);
1585                         if (!arg[9] || *end)
1586                                 usage(pack_usage);
1587                         continue;
1588                 }
1589                 if (!prefixcmp(arg, "--depth=")) {
1590                         char *end;
1591                         depth = strtoul(arg+8, &end, 0);
1592                         if (!arg[8] || *end)
1593                                 usage(pack_usage);
1594                         continue;
1595                 }
1596                 if (!strcmp("--progress", arg)) {
1597                         progress = 1;
1598                         continue;
1599                 }
1600                 if (!strcmp("--all-progress", arg)) {
1601                         progress = 2;
1602                         continue;
1603                 }
1604                 if (!strcmp("-q", arg)) {
1605                         progress = 0;
1606                         continue;
1607                 }
1608                 if (!strcmp("--no-reuse-delta", arg)) {
1609                         no_reuse_delta = 1;
1610                         continue;
1611                 }
1612                 if (!strcmp("--delta-base-offset", arg)) {
1613                         allow_ofs_delta = 1;
1614                         continue;
1615                 }
1616                 if (!strcmp("--stdout", arg)) {
1617                         pack_to_stdout = 1;
1618                         continue;
1619                 }
1620                 if (!strcmp("--revs", arg)) {
1621                         use_internal_rev_list = 1;
1622                         continue;
1623                 }
1624                 if (!strcmp("--unpacked", arg) ||
1625                     !prefixcmp(arg, "--unpacked=") ||
1626                     !strcmp("--reflog", arg) ||
1627                     !strcmp("--all", arg)) {
1628                         use_internal_rev_list = 1;
1629                         if (rp_ac >= rp_ac_alloc - 1) {
1630                                 rp_ac_alloc = alloc_nr(rp_ac_alloc);
1631                                 rp_av = xrealloc(rp_av,
1632                                                  rp_ac_alloc * sizeof(*rp_av));
1633                         }
1634                         rp_av[rp_ac++] = arg;
1635                         continue;
1636                 }
1637                 if (!strcmp("--thin", arg)) {
1638                         use_internal_rev_list = 1;
1639                         thin = 1;
1640                         rp_av[1] = "--objects-edge";
1641                         continue;
1642                 }
1643                 usage(pack_usage);
1644         }
1645
1646         /* Traditionally "pack-objects [options] base extra" failed;
1647          * we would however want to take refs parameter that would
1648          * have been given to upstream rev-list ourselves, which means
1649          * we somehow want to say what the base name is.  So the
1650          * syntax would be:
1651          *
1652          * pack-objects [options] base <refs...>
1653          *
1654          * in other words, we would treat the first non-option as the
1655          * base_name and send everything else to the internal revision
1656          * walker.
1657          */
1658
1659         if (!pack_to_stdout)
1660                 base_name = argv[i++];
1661
1662         if (pack_to_stdout != !base_name)
1663                 usage(pack_usage);
1664
1665         if (!pack_to_stdout && thin)
1666                 die("--thin cannot be used to build an indexable pack.");
1667
1668         prepare_packed_git();
1669
1670         if (progress) {
1671                 fprintf(stderr, "Generating pack...\n");
1672                 setup_progress_signal();
1673         }
1674
1675         if (!use_internal_rev_list)
1676                 read_object_list_from_stdin();
1677         else {
1678                 rp_av[rp_ac] = NULL;
1679                 get_object_list(rp_ac, rp_av);
1680         }
1681
1682         if (progress)
1683                 fprintf(stderr, "Done counting %u objects.\n", nr_objects);
1684         sorted_by_sha = create_final_object_list();
1685         if (non_empty && !nr_result)
1686                 return 0;
1687
1688         SHA1_Init(&ctx);
1689         list = sorted_by_sha;
1690         for (i = 0; i < nr_result; i++) {
1691                 struct object_entry *entry = *list++;
1692                 SHA1_Update(&ctx, entry->sha1, 20);
1693         }
1694         SHA1_Final(object_list_sha1, &ctx);
1695         if (progress && (nr_objects != nr_result))
1696                 fprintf(stderr, "Result has %u objects.\n", nr_result);
1697
1698         if (reuse_cached_pack(object_list_sha1))
1699                 ;
1700         else {
1701                 if (nr_result)
1702                         prepare_pack(window, depth);
1703                 if (progress == 1 && pack_to_stdout) {
1704                         /* the other end usually displays progress itself */
1705                         struct itimerval v = {{0,},};
1706                         setitimer(ITIMER_REAL, &v, NULL);
1707                         signal(SIGALRM, SIG_IGN );
1708                         progress_update = 0;
1709                 }
1710                 write_pack_file();
1711                 if (!pack_to_stdout) {
1712                         write_index_file();
1713                         puts(sha1_to_hex(object_list_sha1));
1714                 }
1715         }
1716         if (progress)
1717                 fprintf(stderr, "Total %u (delta %u), reused %u (delta %u)\n",
1718                         written, written_delta, reused, reused_delta);
1719         return 0;
1720 }