builtin/index-pack.c

   1 #include "builtin.h"
   2 #include "delta.h"
   3 #include "pack.h"
   4 #include "csum-file.h"
   5 #include "blob.h"
   6 #include "commit.h"
   7 #include "tag.h"
   8 #include "tree.h"
   9 #include "progress.h"
  10 #include "fsck.h"
  11 #include "exec_cmd.h"
  12
  13 static const char index_pack_usage[] =
  14 "git index-pack [-v] [-o <index-file>] [--keep | --keep=<msg>] [--verify] [--strict] (<pack-file> | --stdin [--fix-thin] [<pack-file>])";
  15
  16 struct object_entry {
  17         struct pack_idx_entry idx;
  18         unsigned long size;
  19         unsigned int hdr_size;
  20         enum object_type type;
  21         enum object_type real_type;
  22         unsigned delta_depth;
  23         int base_object_no;
  24 };
  25
  26 union delta_base {
  27         unsigned char sha1[20];
  28         off_t offset;
  29 };
  30
  31 struct base_data {
  32         struct base_data *base;
  33         struct base_data *child;
  34         struct object_entry *obj;
  35         void *data;
  36         unsigned long size;
  37 };
  38
  39 /*
  40  * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
  41  * to memcmp() only the first 20 bytes.
  42  */
  43 #define UNION_BASE_SZ   20
  44
  45 #define FLAG_LINK (1u<<20)
  46 #define FLAG_CHECKED (1u<<21)
  47
  48 struct delta_entry {
  49         union delta_base base;
  50         int obj_no;
  51 };
  52
  53 static struct object_entry *objects;
  54 static struct delta_entry *deltas;
  55 static struct base_data *base_cache;
  56 static size_t base_cache_used;
  57 static int nr_objects;
  58 static int nr_deltas;
  59 static int nr_resolved_deltas;
  60
  61 static int from_stdin;
  62 static int strict;
  63 static int verbose;
  64
  65 static struct progress *progress;
  66
  67 /* We always read in 4kB chunks. */
  68 static unsigned char input_buffer[4096];
  69 static unsigned int input_offset, input_len;
  70 static off_t consumed_bytes;
  71 static unsigned deepest_delta;
  72 static git_SHA_CTX input_ctx;
  73 static uint32_t input_crc32;
  74 static int input_fd, output_fd, pack_fd;
  75
  76 static int mark_link(struct object *obj, int type, void *data)
  77 {
  78         if (!obj)
  79                 return -1;
  80
  81         if (type != OBJ_ANY && obj->type != type)
  82                 die("object type mismatch at %s", sha1_to_hex(obj->sha1));
  83
  84         obj->flags |= FLAG_LINK;
  85         return 0;
  86 }
  87
  88 /* The content of each linked object must have been checked
  89    or it must be already present in the object database */
  90 static void check_object(struct object *obj)
  91 {
  92         if (!obj)
  93                 return;
  94
  95         if (!(obj->flags & FLAG_LINK))
  96                 return;
  97
  98         if (!(obj->flags & FLAG_CHECKED)) {
  99                 unsigned long size;
 100                 int type = sha1_object_info(obj->sha1, &size);
 101                 if (type != obj->type || type <= 0)
 102                         die("object of unexpected type");
 103                 obj->flags |= FLAG_CHECKED;
 104                 return;
 105         }
 106 }
 107
 108 static void check_objects(void)
 109 {
 110         unsigned i, max;
 111
 112         max = get_max_object_index();
 113         for (i = 0; i < max; i++)
 114                 check_object(get_indexed_object(i));
 115 }
 116
 117
 118 /* Discard current buffer used content. */
 119 static void flush(void)
 120 {
 121         if (input_offset) {
 122                 if (output_fd >= 0)
 123                         write_or_die(output_fd, input_buffer, input_offset);
 124                 git_SHA1_Update(&input_ctx, input_buffer, input_offset);
 125                 memmove(input_buffer, input_buffer + input_offset, input_len);
 126                 input_offset = 0;
 127         }
 128 }
 129
 130 /*
 131  * Make sure at least "min" bytes are available in the buffer, and
 132  * return the pointer to the buffer.
 133  */
 134 static void *fill(int min)
 135 {
 136         if (min <= input_len)
 137                 return input_buffer + input_offset;
 138         if (min > sizeof(input_buffer))
 139                 die("cannot fill %d bytes", min);
 140         flush();
 141         do {
 142                 ssize_t ret = xread(input_fd, input_buffer + input_len,
 143                                 sizeof(input_buffer) - input_len);
 144                 if (ret <= 0) {
 145                         if (!ret)
 146                                 die("early EOF");
 147                         die_errno("read error on input");
 148                 }
 149                 input_len += ret;
 150                 if (from_stdin)
 151                         display_throughput(progress, consumed_bytes + input_len);
 152         } while (input_len < min);
 153         return input_buffer;
 154 }
 155
 156 static void use(int bytes)
 157 {
 158         if (bytes > input_len)
 159                 die("used more bytes than were available");
 160         input_crc32 = crc32(input_crc32, input_buffer + input_offset, bytes);
 161         input_len -= bytes;
 162         input_offset += bytes;
 163
 164         /* make sure off_t is sufficiently large not to wrap */
 165         if (signed_add_overflows(consumed_bytes, bytes))
 166                 die("pack too large for current definition of off_t");
 167         consumed_bytes += bytes;
 168 }
 169
 170 static const char *open_pack_file(const char *pack_name)
 171 {
 172         if (from_stdin) {
 173                 input_fd = 0;
 174                 if (!pack_name) {
 175                         static char tmp_file[PATH_MAX];
 176                         output_fd = odb_mkstemp(tmp_file, sizeof(tmp_file),
 177                                                 "pack/tmp_pack_XXXXXX");
 178                         pack_name = xstrdup(tmp_file);
 179                 } else
 180                         output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
 181                 if (output_fd < 0)
 182                         die_errno("unable to create '%s'", pack_name);
 183                 pack_fd = output_fd;
 184         } else {
 185                 input_fd = open(pack_name, O_RDONLY);
 186                 if (input_fd < 0)
 187                         die_errno("cannot open packfile '%s'", pack_name);
 188                 output_fd = -1;
 189                 pack_fd = input_fd;
 190         }
 191         git_SHA1_Init(&input_ctx);
 192         return pack_name;
 193 }
 194
 195 static void parse_pack_header(void)
 196 {
 197         struct pack_header *hdr = fill(sizeof(struct pack_header));
 198
 199         /* Header consistency check */
 200         if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 201                 die("pack signature mismatch");
 202         if (!pack_version_ok(hdr->hdr_version))
 203                 die("pack version %"PRIu32" unsupported",
 204                         ntohl(hdr->hdr_version));
 205
 206         nr_objects = ntohl(hdr->hdr_entries);
 207         use(sizeof(struct pack_header));
 208 }
 209
 210 static NORETURN void bad_object(unsigned long offset, const char *format,
 211                        ...) __attribute__((format (printf, 2, 3)));
 212
 213 static NORETURN void bad_object(unsigned long offset, const char *format, ...)
 214 {
 215         va_list params;
 216         char buf[1024];
 217
 218         va_start(params, format);
 219         vsnprintf(buf, sizeof(buf), format, params);
 220         va_end(params);
 221         die("pack has bad object at offset %lu: %s", offset, buf);
 222 }
 223
 224 static void free_base_data(struct base_data *c)
 225 {
 226         if (c->data) {
 227                 free(c->data);
 228                 c->data = NULL;
 229                 base_cache_used -= c->size;
 230         }
 231 }
 232
 233 static void prune_base_data(struct base_data *retain)
 234 {
 235         struct base_data *b;
 236         for (b = base_cache;
 237              base_cache_used > delta_base_cache_limit && b;
 238              b = b->child) {
 239                 if (b->data && b != retain)
 240                         free_base_data(b);
 241         }
 242 }
 243
 244 static void link_base_data(struct base_data *base, struct base_data *c)
 245 {
 246         if (base)
 247                 base->child = c;
 248         else
 249                 base_cache = c;
 250
 251         c->base = base;
 252         c->child = NULL;
 253         if (c->data)
 254                 base_cache_used += c->size;
 255         prune_base_data(c);
 256 }
 257
 258 static void unlink_base_data(struct base_data *c)
 259 {
 260         struct base_data *base = c->base;
 261         if (base)
 262                 base->child = NULL;
 263         else
 264                 base_cache = NULL;
 265         free_base_data(c);
 266 }
 267
 268 static void *unpack_entry_data(unsigned long offset, unsigned long size)
 269 {
 270         int status;
 271         git_zstream stream;
 272         void *buf = xmalloc(size);
 273
 274         memset(&stream, 0, sizeof(stream));
 275         git_inflate_init(&stream);
 276         stream.next_out = buf;
 277         stream.avail_out = size;
 278
 279         do {
 280                 stream.next_in = fill(1);
 281                 stream.avail_in = input_len;
 282                 status = git_inflate(&stream, 0);
 283                 use(input_len - stream.avail_in);
 284         } while (status == Z_OK);
 285         if (stream.total_out != size || status != Z_STREAM_END)
 286                 bad_object(offset, "inflate returned %d", status);
 287         git_inflate_end(&stream);
 288         return buf;
 289 }
 290
 291 static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
 292 {
 293         unsigned char *p;
 294         unsigned long size, c;
 295         off_t base_offset;
 296         unsigned shift;
 297         void *data;
 298
 299         obj->idx.offset = consumed_bytes;
 300         input_crc32 = crc32(0, NULL, 0);
 301
 302         p = fill(1);
 303         c = *p;
 304         use(1);
 305         obj->type = (c >> 4) & 7;
 306         size = (c & 15);
 307         shift = 4;
 308         while (c & 0x80) {
 309                 p = fill(1);
 310                 c = *p;
 311                 use(1);
 312                 size += (c & 0x7f) << shift;
 313                 shift += 7;
 314         }
 315         obj->size = size;
 316
 317         switch (obj->type) {
 318         case OBJ_REF_DELTA:
 319                 hashcpy(delta_base->sha1, fill(20));
 320                 use(20);
 321                 break;
 322         case OBJ_OFS_DELTA:
 323                 memset(delta_base, 0, sizeof(*delta_base));
 324                 p = fill(1);
 325                 c = *p;
 326                 use(1);
 327                 base_offset = c & 127;
 328                 while (c & 128) {
 329                         base_offset += 1;
 330                         if (!base_offset || MSB(base_offset, 7))
 331                                 bad_object(obj->idx.offset, "offset value overflow for delta base object");
 332                         p = fill(1);
 333                         c = *p;
 334                         use(1);
 335                         base_offset = (base_offset << 7) + (c & 127);
 336                 }
 337                 delta_base->offset = obj->idx.offset - base_offset;
 338                 if (delta_base->offset <= 0 || delta_base->offset >= obj->idx.offset)
 339                         bad_object(obj->idx.offset, "delta base offset is out of bound");
 340                 break;
 341         case OBJ_COMMIT:
 342         case OBJ_TREE:
 343         case OBJ_BLOB:
 344         case OBJ_TAG:
 345                 break;
 346         default:
 347                 bad_object(obj->idx.offset, "unknown object type %d", obj->type);
 348         }
 349         obj->hdr_size = consumed_bytes - obj->idx.offset;
 350
 351         data = unpack_entry_data(obj->idx.offset, obj->size);
 352         obj->idx.crc32 = input_crc32;
 353         return data;
 354 }
 355
 356 static void *get_data_from_pack(struct object_entry *obj)
 357 {
 358         off_t from = obj[0].idx.offset + obj[0].hdr_size;
 359         unsigned long len = obj[1].idx.offset - from;
 360         unsigned char *data, *inbuf;
 361         git_zstream stream;
 362         int status;
 363
 364         data = xmalloc(obj->size);
 365         inbuf = xmalloc((len < 64*1024) ? len : 64*1024);
 366
 367         memset(&stream, 0, sizeof(stream));
 368         git_inflate_init(&stream);
 369         stream.next_out = data;
 370         stream.avail_out = obj->size;
 371
 372         do {
 373                 ssize_t n = (len < 64*1024) ? len : 64*1024;
 374                 n = pread(pack_fd, inbuf, n, from);
 375                 if (n < 0)
 376                         die_errno("cannot pread pack file");
 377                 if (!n)
 378                         die("premature end of pack file, %lu bytes missing", len);
 379                 from += n;
 380                 len -= n;
 381                 stream.next_in = inbuf;
 382                 stream.avail_in = n;
 383                 status = git_inflate(&stream, 0);
 384         } while (len && status == Z_OK && !stream.avail_in);
 385
 386         /* This has been inflated OK when first encountered, so... */
 387         if (status != Z_STREAM_END || stream.total_out != obj->size)
 388                 die("serious inflate inconsistency");
 389
 390         git_inflate_end(&stream);
 391         free(inbuf);
 392         return data;
 393 }
 394
 395 static int compare_delta_bases(const union delta_base *base1,
 396                                const union delta_base *base2,
 397                                enum object_type type1,
 398                                enum object_type type2)
 399 {
 400         int cmp = type1 - type2;
 401         if (cmp)
 402                 return cmp;
 403         return memcmp(base1, base2, UNION_BASE_SZ);
 404 }
 405
 406 static int find_delta(const union delta_base *base, enum object_type type)
 407 {
 408         int first = 0, last = nr_deltas;
 409
 410         while (first < last) {
 411                 int next = (first + last) / 2;
 412                 struct delta_entry *delta = &deltas[next];
 413                 int cmp;
 414
 415                 cmp = compare_delta_bases(base, &delta->base,
 416                                           type, objects[delta->obj_no].type);
 417                 if (!cmp)
 418                         return next;
 419                 if (cmp < 0) {
 420                         last = next;
 421                         continue;
 422                 }
 423                 first = next+1;
 424         }
 425         return -first-1;
 426 }
 427
 428 static void find_delta_children(const union delta_base *base,
 429                                 int *first_index, int *last_index,
 430                                 enum object_type type)
 431 {
 432         int first = find_delta(base, type);
 433         int last = first;
 434         int end = nr_deltas - 1;
 435
 436         if (first < 0) {
 437                 *first_index = 0;
 438                 *last_index = -1;
 439                 return;
 440         }
 441         while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
 442                 --first;
 443         while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
 444                 ++last;
 445         *first_index = first;
 446         *last_index = last;
 447 }
 448
 449 static void sha1_object(const void *data, unsigned long size,
 450                         enum object_type type, unsigned char *sha1)
 451 {
 452         hash_sha1_file(data, size, typename(type), sha1);
 453         if (has_sha1_file(sha1)) {
 454                 void *has_data;
 455                 enum object_type has_type;
 456                 unsigned long has_size;
 457                 has_data = read_sha1_file(sha1, &has_type, &has_size);
 458                 if (!has_data)
 459                         die("cannot read existing object %s", sha1_to_hex(sha1));
 460                 if (size != has_size || type != has_type ||
 461                     memcmp(data, has_data, size) != 0)
 462                         die("SHA1 COLLISION FOUND WITH %s !", sha1_to_hex(sha1));
 463                 free(has_data);
 464         }
 465         if (strict) {
 466                 if (type == OBJ_BLOB) {
 467                         struct blob *blob = lookup_blob(sha1);
 468                         if (blob)
 469                                 blob->object.flags |= FLAG_CHECKED;
 470                         else
 471                                 die("invalid blob object %s", sha1_to_hex(sha1));
 472                 } else {
 473                         struct object *obj;
 474                         int eaten;
 475                         void *buf = (void *) data;
 476
 477                         /*
 478                          * we do not need to free the memory here, as the
 479                          * buf is deleted by the caller.
 480                          */
 481                         obj = parse_object_buffer(sha1, type, size, buf, &eaten);
 482                         if (!obj)
 483                                 die("invalid %s", typename(type));
 484                         if (fsck_object(obj, 1, fsck_error_function))
 485                                 die("Error in object");
 486                         if (fsck_walk(obj, mark_link, NULL))
 487                                 die("Not all child objects of %s are reachable", sha1_to_hex(obj->sha1));
 488
 489                         if (obj->type == OBJ_TREE) {
 490                                 struct tree *item = (struct tree *) obj;
 491                                 item->buffer = NULL;
 492                         }
 493                         if (obj->type == OBJ_COMMIT) {
 494                                 struct commit *commit = (struct commit *) obj;
 495                                 commit->buffer = NULL;
 496                         }
 497                         obj->flags |= FLAG_CHECKED;
 498                 }
 499         }
 500 }
 501
 502 static int is_delta_type(enum object_type type)
 503 {
 504         return (type == OBJ_REF_DELTA || type == OBJ_OFS_DELTA);
 505 }
 506
 507 static void *get_base_data(struct base_data *c)
 508 {
 509         if (!c->data) {
 510                 struct object_entry *obj = c->obj;
 511
 512                 if (is_delta_type(obj->type)) {
 513                         void *base = get_base_data(c->base);
 514                         void *raw = get_data_from_pack(obj);
 515                         c->data = patch_delta(
 516                                 base, c->base->size,
 517                                 raw, obj->size,
 518                                 &c->size);
 519                         free(raw);
 520                         if (!c->data)
 521                                 bad_object(obj->idx.offset, "failed to apply delta");
 522                 } else {
 523                         c->data = get_data_from_pack(obj);
 524                         c->size = obj->size;
 525                 }
 526
 527                 base_cache_used += c->size;
 528                 prune_base_data(c);
 529         }
 530         return c->data;
 531 }
 532
 533 static void resolve_delta(struct object_entry *delta_obj,
 534                           struct base_data *base, struct base_data *result)
 535 {
 536         void *base_data, *delta_data;
 537
 538         delta_obj->real_type = base->obj->real_type;
 539         delta_obj->delta_depth = base->obj->delta_depth + 1;
 540         if (deepest_delta < delta_obj->delta_depth)
 541                 deepest_delta = delta_obj->delta_depth;
 542         delta_obj->base_object_no = base->obj - objects;
 543         delta_data = get_data_from_pack(delta_obj);
 544         base_data = get_base_data(base);
 545         result->obj = delta_obj;
 546         result->data = patch_delta(base_data, base->size,
 547                                    delta_data, delta_obj->size, &result->size);
 548         free(delta_data);
 549         if (!result->data)
 550                 bad_object(delta_obj->idx.offset, "failed to apply delta");
 551         sha1_object(result->data, result->size, delta_obj->real_type,
 552                     delta_obj->idx.sha1);
 553         nr_resolved_deltas++;
 554 }
 555
 556 static void find_unresolved_deltas(struct base_data *base,
 557                                    struct base_data *prev_base)
 558 {
 559         int i, ref_first, ref_last, ofs_first, ofs_last;
 560
 561         /*
 562          * This is a recursive function. Those brackets should help reducing
 563          * stack usage by limiting the scope of the delta_base union.
 564          */
 565         {
 566                 union delta_base base_spec;
 567
 568                 hashcpy(base_spec.sha1, base->obj->idx.sha1);
 569                 find_delta_children(&base_spec,
 570                                     &ref_first, &ref_last, OBJ_REF_DELTA);
 571
 572                 memset(&base_spec, 0, sizeof(base_spec));
 573                 base_spec.offset = base->obj->idx.offset;
 574                 find_delta_children(&base_spec,
 575                                     &ofs_first, &ofs_last, OBJ_OFS_DELTA);
 576         }
 577
 578         if (ref_last == -1 && ofs_last == -1) {
 579                 free(base->data);
 580                 return;
 581         }
 582
 583         link_base_data(prev_base, base);
 584
 585         for (i = ref_first; i <= ref_last; i++) {
 586                 struct object_entry *child = objects + deltas[i].obj_no;
 587                 struct base_data result;
 588
 589                 assert(child->real_type == OBJ_REF_DELTA);
 590                 resolve_delta(child, base, &result);
 591                 if (i == ref_last && ofs_last == -1)
 592                         free_base_data(base);
 593                 find_unresolved_deltas(&result, base);
 594         }
 595
 596         for (i = ofs_first; i <= ofs_last; i++) {
 597                 struct object_entry *child = objects + deltas[i].obj_no;
 598                 struct base_data result;
 599
 600                 assert(child->real_type == OBJ_OFS_DELTA);
 601                 resolve_delta(child, base, &result);
 602                 if (i == ofs_last)
 603                         free_base_data(base);
 604                 find_unresolved_deltas(&result, base);
 605         }
 606
 607         unlink_base_data(base);
 608 }
 609
 610 static int compare_delta_entry(const void *a, const void *b)
 611 {
 612         const struct delta_entry *delta_a = a;
 613         const struct delta_entry *delta_b = b;
 614
 615         /* group by type (ref vs ofs) and then by value (sha-1 or offset) */
 616         return compare_delta_bases(&delta_a->base, &delta_b->base,
 617                                    objects[delta_a->obj_no].type,
 618                                    objects[delta_b->obj_no].type);
 619 }
 620
 621 /* Parse all objects and return the pack content SHA1 hash */
 622 static void parse_pack_objects(unsigned char *sha1)
 623 {
 624         int i;
 625         struct delta_entry *delta = deltas;
 626         struct stat st;
 627
 628         /*
 629          * First pass:
 630          * - find locations of all objects;
 631          * - calculate SHA1 of all non-delta objects;
 632          * - remember base (SHA1 or offset) for all deltas.
 633          */
 634         if (verbose)
 635                 progress = start_progress(
 636                                 from_stdin ? "Receiving objects" : "Indexing objects",
 637                                 nr_objects);
 638         for (i = 0; i < nr_objects; i++) {
 639                 struct object_entry *obj = &objects[i];
 640                 void *data = unpack_raw_entry(obj, &delta->base);
 641                 obj->real_type = obj->type;
 642                 if (is_delta_type(obj->type)) {
 643                         nr_deltas++;
 644                         delta->obj_no = i;
 645                         delta++;
 646                 } else
 647                         sha1_object(data, obj->size, obj->type, obj->idx.sha1);
 648                 free(data);
 649                 display_progress(progress, i+1);
 650         }
 651         objects[i].idx.offset = consumed_bytes;
 652         stop_progress(&progress);
 653
 654         /* Check pack integrity */
 655         flush();
 656         git_SHA1_Final(sha1, &input_ctx);
 657         if (hashcmp(fill(20), sha1))
 658                 die("pack is corrupted (SHA1 mismatch)");
 659         use(20);
 660
 661         /* If input_fd is a file, we should have reached its end now. */
 662         if (fstat(input_fd, &st))
 663                 die_errno("cannot fstat packfile");
 664         if (S_ISREG(st.st_mode) &&
 665                         lseek(input_fd, 0, SEEK_CUR) - input_len != st.st_size)
 666                 die("pack has junk at the end");
 667
 668         if (!nr_deltas)
 669                 return;
 670
 671         /* Sort deltas by base SHA1/offset for fast searching */
 672         qsort(deltas, nr_deltas, sizeof(struct delta_entry),
 673               compare_delta_entry);
 674
 675         /*
 676          * Second pass:
 677          * - for all non-delta objects, look if it is used as a base for
 678          *   deltas;
 679          * - if used as a base, uncompress the object and apply all deltas,
 680          *   recursively checking if the resulting object is used as a base
 681          *   for some more deltas.
 682          */
 683         if (verbose)
 684                 progress = start_progress("Resolving deltas", nr_deltas);
 685         for (i = 0; i < nr_objects; i++) {
 686                 struct object_entry *obj = &objects[i];
 687                 struct base_data base_obj;
 688
 689                 if (is_delta_type(obj->type))
 690                         continue;
 691                 base_obj.obj = obj;
 692                 base_obj.data = NULL;
 693                 find_unresolved_deltas(&base_obj, NULL);
 694                 display_progress(progress, nr_resolved_deltas);
 695         }
 696 }
 697
 698 static int write_compressed(struct sha1file *f, void *in, unsigned int size)
 699 {
 700         git_zstream stream;
 701         int status;
 702         unsigned char outbuf[4096];
 703
 704         memset(&stream, 0, sizeof(stream));
 705         git_deflate_init(&stream, zlib_compression_level);
 706         stream.next_in = in;
 707         stream.avail_in = size;
 708
 709         do {
 710                 stream.next_out = outbuf;
 711                 stream.avail_out = sizeof(outbuf);
 712                 status = git_deflate(&stream, Z_FINISH);
 713                 sha1write(f, outbuf, sizeof(outbuf) - stream.avail_out);
 714         } while (status == Z_OK);
 715
 716         if (status != Z_STREAM_END)
 717                 die("unable to deflate appended object (%d)", status);
 718         size = stream.total_out;
 719         git_deflate_end(&stream);
 720         return size;
 721 }
 722
 723 static struct object_entry *append_obj_to_pack(struct sha1file *f,
 724                                const unsigned char *sha1, void *buf,
 725                                unsigned long size, enum object_type type)
 726 {
 727         struct object_entry *obj = &objects[nr_objects++];
 728         unsigned char header[10];
 729         unsigned long s = size;
 730         int n = 0;
 731         unsigned char c = (type << 4) | (s & 15);
 732         s >>= 4;
 733         while (s) {
 734                 header[n++] = c | 0x80;
 735                 c = s & 0x7f;
 736                 s >>= 7;
 737         }
 738         header[n++] = c;
 739         crc32_begin(f);
 740         sha1write(f, header, n);
 741         obj[0].size = size;
 742         obj[0].hdr_size = n;
 743         obj[0].type = type;
 744         obj[0].real_type = type;
 745         obj[1].idx.offset = obj[0].idx.offset + n;
 746         obj[1].idx.offset += write_compressed(f, buf, size);
 747         obj[0].idx.crc32 = crc32_end(f);
 748         sha1flush(f);
 749         hashcpy(obj->idx.sha1, sha1);
 750         return obj;
 751 }
 752
 753 static int delta_pos_compare(const void *_a, const void *_b)
 754 {
 755         struct delta_entry *a = *(struct delta_entry **)_a;
 756         struct delta_entry *b = *(struct delta_entry **)_b;
 757         return a->obj_no - b->obj_no;
 758 }
 759
 760 static void fix_unresolved_deltas(struct sha1file *f, int nr_unresolved)
 761 {
 762         struct delta_entry **sorted_by_pos;
 763         int i, n = 0;
 764
 765         /*
 766          * Since many unresolved deltas may well be themselves base objects
 767          * for more unresolved deltas, we really want to include the
 768          * smallest number of base objects that would cover as much delta
 769          * as possible by picking the
 770          * trunc deltas first, allowing for other deltas to resolve without
 771          * additional base objects.  Since most base objects are to be found
 772          * before deltas depending on them, a good heuristic is to start
 773          * resolving deltas in the same order as their position in the pack.
 774          */
 775         sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
 776         for (i = 0; i < nr_deltas; i++) {
 777                 if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
 778                         continue;
 779                 sorted_by_pos[n++] = &deltas[i];
 780         }
 781         qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);
 782
 783         for (i = 0; i < n; i++) {
 784                 struct delta_entry *d = sorted_by_pos[i];
 785                 enum object_type type;
 786                 struct base_data base_obj;
 787
 788                 if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
 789                         continue;
 790                 base_obj.data = read_sha1_file(d->base.sha1, &type, &base_obj.size);
 791                 if (!base_obj.data)
 792                         continue;
 793
 794                 if (check_sha1_signature(d->base.sha1, base_obj.data,
 795                                 base_obj.size, typename(type)))
 796                         die("local object %s is corrupt", sha1_to_hex(d->base.sha1));
 797                 base_obj.obj = append_obj_to_pack(f, d->base.sha1,
 798                                         base_obj.data, base_obj.size, type);
 799                 find_unresolved_deltas(&base_obj, NULL);
 800                 display_progress(progress, nr_resolved_deltas);
 801         }
 802         free(sorted_by_pos);
 803 }
 804
 805 static void final(const char *final_pack_name, const char *curr_pack_name,
 806                   const char *final_index_name, const char *curr_index_name,
 807                   const char *keep_name, const char *keep_msg,
 808                   unsigned char *sha1)
 809 {
 810         const char *report = "pack";
 811         char name[PATH_MAX];
 812         int err;
 813
 814         if (!from_stdin) {
 815                 close(input_fd);
 816         } else {
 817                 fsync_or_die(output_fd, curr_pack_name);
 818                 err = close(output_fd);
 819                 if (err)
 820                         die_errno("error while closing pack file");
 821         }
 822
 823         if (keep_msg) {
 824                 int keep_fd, keep_msg_len = strlen(keep_msg);
 825
 826                 if (!keep_name)
 827                         keep_fd = odb_pack_keep(name, sizeof(name), sha1);
 828                 else
 829                         keep_fd = open(keep_name, O_RDWR|O_CREAT|O_EXCL, 0600);
 830
 831                 if (keep_fd < 0) {
 832                         if (errno != EEXIST)
 833                                 die_errno("cannot write keep file '%s'",
 834                                           keep_name);
 835                 } else {
 836                         if (keep_msg_len > 0) {
 837                                 write_or_die(keep_fd, keep_msg, keep_msg_len);
 838                                 write_or_die(keep_fd, "\n", 1);
 839                         }
 840                         if (close(keep_fd) != 0)
 841                                 die_errno("cannot close written keep file '%s'",
 842                                     keep_name);
 843                         report = "keep";
 844                 }
 845         }
 846
 847         if (final_pack_name != curr_pack_name) {
 848                 if (!final_pack_name) {
 849                         snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
 850                                  get_object_directory(), sha1_to_hex(sha1));
 851                         final_pack_name = name;
 852                 }
 853                 if (move_temp_to_file(curr_pack_name, final_pack_name))
 854                         die("cannot store pack file");
 855         } else if (from_stdin)
 856                 chmod(final_pack_name, 0444);
 857
 858         if (final_index_name != curr_index_name) {
 859                 if (!final_index_name) {
 860                         snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
 861                                  get_object_directory(), sha1_to_hex(sha1));
 862                         final_index_name = name;
 863                 }
 864                 if (move_temp_to_file(curr_index_name, final_index_name))
 865                         die("cannot store index file");
 866         } else
 867                 chmod(final_index_name, 0444);
 868
 869         if (!from_stdin) {
 870                 printf("%s\n", sha1_to_hex(sha1));
 871         } else {
 872                 char buf[48];
 873                 int len = snprintf(buf, sizeof(buf), "%s\t%s\n",
 874                                    report, sha1_to_hex(sha1));
 875                 write_or_die(1, buf, len);
 876
 877                 /*
 878                  * Let's just mimic git-unpack-objects here and write
 879                  * the last part of the input buffer to stdout.
 880                  */
 881                 while (input_len) {
 882                         err = xwrite(1, input_buffer + input_offset, input_len);
 883                         if (err <= 0)
 884                                 break;
 885                         input_len -= err;
 886                         input_offset += err;
 887                 }
 888         }
 889 }
 890
 891 static int git_index_pack_config(const char *k, const char *v, void *cb)
 892 {
 893         struct pack_idx_option *opts = cb;
 894
 895         if (!strcmp(k, "pack.indexversion")) {
 896                 opts->version = git_config_int(k, v);
 897                 if (opts->version > 2)
 898                         die("bad pack.indexversion=%"PRIu32, opts->version);
 899                 return 0;
 900         }
 901         return git_default_config(k, v, cb);
 902 }
 903
 904 static int cmp_uint32(const void *a_, const void *b_)
 905 {
 906         uint32_t a = *((uint32_t *)a_);
 907         uint32_t b = *((uint32_t *)b_);
 908
 909         return (a < b) ? -1 : (a != b);
 910 }
 911
 912 static void read_v2_anomalous_offsets(struct packed_git *p,
 913                                       struct pack_idx_option *opts)
 914 {
 915         const uint32_t *idx1, *idx2;
 916         uint32_t i;
 917
 918         /* The address of the 4-byte offset table */
 919         idx1 = (((const uint32_t *)p->index_data)
 920                 + 2 /* 8-byte header */
 921                 + 256 /* fan out */
 922                 + 5 * p->num_objects /* 20-byte SHA-1 table */
 923                 + p->num_objects /* CRC32 table */
 924                 );
 925
 926         /* The address of the 8-byte offset table */
 927         idx2 = idx1 + p->num_objects;
 928
 929         for (i = 0; i < p->num_objects; i++) {
 930                 uint32_t off = ntohl(idx1[i]);
 931                 if (!(off & 0x80000000))
 932                         continue;
 933                 off = off & 0x7fffffff;
 934                 if (idx2[off * 2])
 935                         continue;
 936                 /*
 937                  * The real offset is ntohl(idx2[off * 2]) in high 4
 938                  * octets, and ntohl(idx2[off * 2 + 1]) in low 4
 939                  * octets.  But idx2[off * 2] is Zero!!!
 940                  */
 941                 ALLOC_GROW(opts->anomaly, opts->anomaly_nr + 1, opts->anomaly_alloc);
 942                 opts->anomaly[opts->anomaly_nr++] = ntohl(idx2[off * 2 + 1]);
 943         }
 944
 945         if (1 < opts->anomaly_nr)
 946                 qsort(opts->anomaly, opts->anomaly_nr, sizeof(uint32_t), cmp_uint32);
 947 }
 948
 949 static void read_idx_option(struct pack_idx_option *opts, const char *pack_name)
 950 {
 951         struct packed_git *p = add_packed_git(pack_name, strlen(pack_name), 1);
 952
 953         if (!p)
 954                 die("Cannot open existing pack file '%s'", pack_name);
 955         if (open_pack_index(p))
 956                 die("Cannot open existing pack idx file for '%s'", pack_name);
 957
 958         /* Read the attributes from the existing idx file */
 959         opts->version = p->index_version;
 960
 961         if (opts->version == 2)
 962                 read_v2_anomalous_offsets(p, opts);
 963
 964         /*
 965          * Get rid of the idx file as we do not need it anymore.
 966          * NEEDSWORK: extract this bit from free_pack_by_name() in
 967          * sha1_file.c, perhaps?  It shouldn't matter very much as we
 968          * know we haven't installed this pack (hence we never have
 969          * read anything from it).
 970          */
 971         close_pack_index(p);
 972         free(p);
 973 }
 974
 975 static void show_pack_info(int stat_only)
 976 {
 977         int i, baseobjects = nr_objects - nr_deltas;
 978         unsigned long *chain_histogram = NULL;
 979
 980         if (deepest_delta)
 981                 chain_histogram = xcalloc(deepest_delta, sizeof(unsigned long));
 982
 983         for (i = 0; i < nr_objects; i++) {
 984                 struct object_entry *obj = &objects[i];
 985
 986                 if (is_delta_type(obj->type))
 987                         chain_histogram[obj->delta_depth - 1]++;
 988                 if (stat_only)
 989                         continue;
 990                 printf("%s %-6s %lu %lu %"PRIuMAX,
 991                        sha1_to_hex(obj->idx.sha1),
 992                        typename(obj->real_type), obj->size,
 993                        (unsigned long)(obj[1].idx.offset - obj->idx.offset),
 994                        (uintmax_t)obj->idx.offset);
 995                 if (is_delta_type(obj->type)) {
 996                         struct object_entry *bobj = &objects[obj->base_object_no];
 997                         printf(" %u %s", obj->delta_depth, sha1_to_hex(bobj->idx.sha1));
 998                 }
 999                 putchar('\n');
1000         }
1001
1002         if (baseobjects)
1003                 printf("non delta: %d object%s\n",
1004                        baseobjects, baseobjects > 1 ? "s" : "");
1005         for (i = 0; i < deepest_delta; i++) {
1006                 if (!chain_histogram[i])
1007                         continue;
1008                 printf("chain length = %d: %lu object%s\n",
1009                        i + 1,
1010                        chain_histogram[i],
1011                        chain_histogram[i] > 1 ? "s" : "");
1012         }
1013 }
1014
1015 int cmd_index_pack(int argc, const char **argv, const char *prefix)
1016 {
1017         int i, fix_thin_pack = 0, verify = 0, stat_only = 0, stat = 0;
1018         const char *curr_pack, *curr_index;
1019         const char *index_name = NULL, *pack_name = NULL;
1020         const char *keep_name = NULL, *keep_msg = NULL;
1021         char *index_name_buf = NULL, *keep_name_buf = NULL;
1022         struct pack_idx_entry **idx_objects;
1023         struct pack_idx_option opts;
1024         unsigned char pack_sha1[20];
1025
1026         if (argc == 2 && !strcmp(argv[1], "-h"))
1027                 usage(index_pack_usage);
1028
1029         read_replace_refs = 0;
1030
1031         reset_pack_idx_option(&opts);
1032         git_config(git_index_pack_config, &opts);
1033         if (prefix && chdir(prefix))
1034                 die("Cannot come back to cwd");
1035
1036         for (i = 1; i < argc; i++) {
1037                 const char *arg = argv[i];
1038
1039                 if (*arg == '-') {
1040                         if (!strcmp(arg, "--stdin")) {
1041                                 from_stdin = 1;
1042                         } else if (!strcmp(arg, "--fix-thin")) {
1043                                 fix_thin_pack = 1;
1044                         } else if (!strcmp(arg, "--strict")) {
1045                                 strict = 1;
1046                         } else if (!strcmp(arg, "--verify")) {
1047                                 verify = 1;
1048                         } else if (!strcmp(arg, "--verify-stat")) {
1049                                 verify = 1;
1050                                 stat = 1;
1051                         } else if (!strcmp(arg, "--verify-stat-only")) {
1052                                 verify = 1;
1053                                 stat = 1;
1054                                 stat_only = 1;
1055                         } else if (!strcmp(arg, "--keep")) {
1056                                 keep_msg = "";
1057                         } else if (!prefixcmp(arg, "--keep=")) {
1058                                 keep_msg = arg + 7;
1059                         } else if (!prefixcmp(arg, "--pack_header=")) {
1060                                 struct pack_header *hdr;
1061                                 char *c;
1062
1063                                 hdr = (struct pack_header *)input_buffer;
1064                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
1065                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
1066                                 if (*c != ',')
1067                                         die("bad %s", arg);
1068                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
1069                                 if (*c)
1070                                         die("bad %s", arg);
1071                                 input_len = sizeof(*hdr);
1072                         } else if (!strcmp(arg, "-v")) {
1073                                 verbose = 1;
1074                         } else if (!strcmp(arg, "-o")) {
1075                                 if (index_name || (i+1) >= argc)
1076                                         usage(index_pack_usage);
1077                                 index_name = argv[++i];
1078                         } else if (!prefixcmp(arg, "--index-version=")) {
1079                                 char *c;
1080                                 opts.version = strtoul(arg + 16, &c, 10);
1081                                 if (opts.version > 2)
1082                                         die("bad %s", arg);
1083                                 if (*c == ',')
1084                                         opts.off32_limit = strtoul(c+1, &c, 0);
1085                                 if (*c || opts.off32_limit & 0x80000000)
1086                                         die("bad %s", arg);
1087                         } else
1088                                 usage(index_pack_usage);
1089                         continue;
1090                 }
1091
1092                 if (pack_name)
1093                         usage(index_pack_usage);
1094                 pack_name = arg;
1095         }
1096
1097         if (!pack_name && !from_stdin)
1098                 usage(index_pack_usage);
1099         if (fix_thin_pack && !from_stdin)
1100                 die("--fix-thin cannot be used without --stdin");
1101         if (!index_name && pack_name) {
1102                 int len = strlen(pack_name);
1103                 if (!has_extension(pack_name, ".pack"))
1104                         die("packfile name '%s' does not end with '.pack'",
1105                             pack_name);
1106                 index_name_buf = xmalloc(len);
1107                 memcpy(index_name_buf, pack_name, len - 5);
1108                 strcpy(index_name_buf + len - 5, ".idx");
1109                 index_name = index_name_buf;
1110         }
1111         if (keep_msg && !keep_name && pack_name) {
1112                 int len = strlen(pack_name);
1113                 if (!has_extension(pack_name, ".pack"))
1114                         die("packfile name '%s' does not end with '.pack'",
1115                             pack_name);
1116                 keep_name_buf = xmalloc(len);
1117                 memcpy(keep_name_buf, pack_name, len - 5);
1118                 strcpy(keep_name_buf + len - 5, ".keep");
1119                 keep_name = keep_name_buf;
1120         }
1121         if (verify) {
1122                 if (!index_name)
1123                         die("--verify with no packfile name given");
1124                 read_idx_option(&opts, index_name);
1125                 opts.flags |= WRITE_IDX_VERIFY | WRITE_IDX_STRICT;
1126         }
1127         if (strict)
1128                 opts.flags |= WRITE_IDX_STRICT;
1129
1130         curr_pack = open_pack_file(pack_name);
1131         parse_pack_header();
1132         objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
1133         deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
1134         parse_pack_objects(pack_sha1);
1135         if (nr_deltas == nr_resolved_deltas) {
1136                 stop_progress(&progress);
1137                 /* Flush remaining pack final 20-byte SHA1. */
1138                 flush();
1139         } else {
1140                 if (fix_thin_pack) {
1141                         struct sha1file *f;
1142                         unsigned char read_sha1[20], tail_sha1[20];
1143                         char msg[48];
1144                         int nr_unresolved = nr_deltas - nr_resolved_deltas;
1145                         int nr_objects_initial = nr_objects;
1146                         if (nr_unresolved <= 0)
1147                                 die("confusion beyond insanity");
1148                         objects = xrealloc(objects,
1149                                            (nr_objects + nr_unresolved + 1)
1150                                            * sizeof(*objects));
1151                         f = sha1fd(output_fd, curr_pack);
1152                         fix_unresolved_deltas(f, nr_unresolved);
1153                         sprintf(msg, "completed with %d local objects",
1154                                 nr_objects - nr_objects_initial);
1155                         stop_progress_msg(&progress, msg);
1156                         sha1close(f, tail_sha1, 0);
1157                         hashcpy(read_sha1, pack_sha1);
1158                         fixup_pack_header_footer(output_fd, pack_sha1,
1159                                                  curr_pack, nr_objects,
1160                                                  read_sha1, consumed_bytes-20);
1161                         if (hashcmp(read_sha1, tail_sha1) != 0)
1162                                 die("Unexpected tail checksum for %s "
1163                                     "(disk corruption?)", curr_pack);
1164                 }
1165                 if (nr_deltas != nr_resolved_deltas)
1166                         die("pack has %d unresolved deltas",
1167                             nr_deltas - nr_resolved_deltas);
1168         }
1169         free(deltas);
1170         if (strict)
1171                 check_objects();
1172
1173         if (stat)
1174                 show_pack_info(stat_only);
1175
1176         idx_objects = xmalloc((nr_objects) * sizeof(struct pack_idx_entry *));
1177         for (i = 0; i < nr_objects; i++)
1178                 idx_objects[i] = &objects[i].idx;
1179         curr_index = write_idx_file(index_name, idx_objects, nr_objects, &opts, pack_sha1);
1180         free(idx_objects);
1181
1182         if (!verify)
1183                 final(pack_name, curr_pack,
1184                       index_name, curr_index,
1185                       keep_name, keep_msg,
1186                       pack_sha1);
1187         else
1188                 close(input_fd);
1189         free(objects);
1190         free(index_name_buf);
1191         free(keep_name_buf);
1192         if (pack_name == NULL)
1193                 free((void *) curr_pack);
1194         if (index_name == NULL)
1195                 free((void *) curr_index);
1196
1197         return 0;
1198 }