builtin/index-pack.c

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