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
  10 static const char index_pack_usage[] =
  11 "git-index-pack [-o <index-file>] { <pack-file> | --stdin [<pack-file>] }";
  12
  13 struct object_entry
  14 {
  15         unsigned long offset;
  16         unsigned long size;
  17         unsigned int hdr_size;
  18         enum object_type type;
  19         enum object_type real_type;
  20         unsigned char sha1[20];
  21 };
  22
  23 union delta_base {
  24         unsigned char sha1[20];
  25         unsigned long offset;
  26 };
  27
  28 /*
  29  * Even if sizeof(union delta_base) == 24 on 64-bit archs, we really want
  30  * to memcmp() only the first 20 bytes.
  31  */
  32 #define UNION_BASE_SZ   20
  33
  34 struct delta_entry
  35 {
  36         struct object_entry *obj;
  37         union delta_base base;
  38 };
  39
  40 static struct object_entry *objects;
  41 static struct delta_entry *deltas;
  42 static int nr_objects;
  43 static int nr_deltas;
  44
  45 static int from_stdin;
  46
  47 /* We always read in 4kB chunks. */
  48 static unsigned char input_buffer[4096];
  49 static unsigned long input_offset, input_len, consumed_bytes;
  50 static SHA_CTX input_ctx;
  51 static int input_fd, output_fd, mmap_fd;
  52
  53 /*
  54  * Make sure at least "min" bytes are available in the buffer, and
  55  * return the pointer to the buffer.
  56  */
  57 static void * fill(int min)
  58 {
  59         if (min <= input_len)
  60                 return input_buffer + input_offset;
  61         if (min > sizeof(input_buffer))
  62                 die("cannot fill %d bytes", min);
  63         if (input_offset) {
  64                 if (output_fd >= 0)
  65                         write_or_die(output_fd, input_buffer, input_offset);
  66                 SHA1_Update(&input_ctx, input_buffer, input_offset);
  67                 memcpy(input_buffer, input_buffer + input_offset, input_len);
  68                 input_offset = 0;
  69         }
  70         do {
  71                 int ret = xread(input_fd, input_buffer + input_len,
  72                                 sizeof(input_buffer) - input_len);
  73                 if (ret <= 0) {
  74                         if (!ret)
  75                                 die("early EOF");
  76                         die("read error on input: %s", strerror(errno));
  77                 }
  78                 input_len += ret;
  79         } while (input_len < min);
  80         return input_buffer;
  81 }
  82
  83 static void use(int bytes)
  84 {
  85         if (bytes > input_len)
  86                 die("used more bytes than were available");
  87         input_len -= bytes;
  88         input_offset += bytes;
  89         consumed_bytes += bytes;
  90 }
  91
  92 static const char * open_pack_file(const char *pack_name)
  93 {
  94         if (from_stdin) {
  95                 input_fd = 0;
  96                 if (!pack_name) {
  97                         static char tmpfile[PATH_MAX];
  98                         snprintf(tmpfile, sizeof(tmpfile),
  99                                  "%s/pack_XXXXXX", get_object_directory());
 100                         output_fd = mkstemp(tmpfile);
 101                         pack_name = xstrdup(tmpfile);
 102                 } else
 103                         output_fd = open(pack_name, O_CREAT|O_EXCL|O_RDWR, 0600);
 104                 if (output_fd < 0)
 105                         die("unable to create %s: %s\n", pack_name, strerror(errno));
 106                 mmap_fd = output_fd;
 107         } else {
 108                 input_fd = open(pack_name, O_RDONLY);
 109                 if (input_fd < 0)
 110                         die("cannot open packfile '%s': %s",
 111                             pack_name, strerror(errno));
 112                 output_fd = -1;
 113                 mmap_fd = input_fd;
 114         }
 115         SHA1_Init(&input_ctx);
 116         return pack_name;
 117 }
 118
 119 static void parse_pack_header(void)
 120 {
 121         struct pack_header *hdr = fill(sizeof(struct pack_header));
 122
 123         /* Header consistency check */
 124         if (hdr->hdr_signature != htonl(PACK_SIGNATURE))
 125                 die("pack signature mismatch");
 126         if (!pack_version_ok(hdr->hdr_version))
 127                 die("pack version %d unsupported", ntohl(hdr->hdr_version));
 128
 129         nr_objects = ntohl(hdr->hdr_entries);
 130         use(sizeof(struct pack_header));
 131         /*fprintf(stderr, "Indexing %d objects\n", nr_objects);*/
 132 }
 133
 134 static void bad_object(unsigned long offset, const char *format,
 135                        ...) NORETURN __attribute__((format (printf, 2, 3)));
 136
 137 static void bad_object(unsigned long offset, const char *format, ...)
 138 {
 139         va_list params;
 140         char buf[1024];
 141
 142         va_start(params, format);
 143         vsnprintf(buf, sizeof(buf), format, params);
 144         va_end(params);
 145         die("pack has bad object at offset %lu: %s", offset, buf);
 146 }
 147
 148 static void *unpack_entry_data(unsigned long offset, unsigned long size)
 149 {
 150         z_stream stream;
 151         void *buf = xmalloc(size);
 152
 153         memset(&stream, 0, sizeof(stream));
 154         stream.next_out = buf;
 155         stream.avail_out = size;
 156         stream.next_in = fill(1);
 157         stream.avail_in = input_len;
 158         inflateInit(&stream);
 159
 160         for (;;) {
 161                 int ret = inflate(&stream, 0);
 162                 use(input_len - stream.avail_in);
 163                 if (stream.total_out == size && ret == Z_STREAM_END)
 164                         break;
 165                 if (ret != Z_OK)
 166                         bad_object(offset, "inflate returned %d", ret);
 167                 stream.next_in = fill(1);
 168                 stream.avail_in = input_len;
 169         }
 170         inflateEnd(&stream);
 171         return buf;
 172 }
 173
 174 static void *unpack_raw_entry(struct object_entry *obj, union delta_base *delta_base)
 175 {
 176         unsigned char *p, c;
 177         unsigned long size, base_offset;
 178         unsigned shift;
 179
 180         obj->offset = consumed_bytes;
 181
 182         p = fill(1);
 183         c = *p;
 184         use(1);
 185         obj->type = (c >> 4) & 7;
 186         size = (c & 15);
 187         shift = 4;
 188         while (c & 0x80) {
 189                 p = fill(1);
 190                 c = *p;
 191                 use(1);
 192                 size += (c & 0x7fUL) << shift;
 193                 shift += 7;
 194         }
 195         obj->size = size;
 196
 197         switch (obj->type) {
 198         case OBJ_REF_DELTA:
 199                 hashcpy(delta_base->sha1, fill(20));
 200                 use(20);
 201                 break;
 202         case OBJ_OFS_DELTA:
 203                 memset(delta_base, 0, sizeof(*delta_base));
 204                 p = fill(1);
 205                 c = *p;
 206                 use(1);
 207                 base_offset = c & 127;
 208                 while (c & 128) {
 209                         base_offset += 1;
 210                         if (!base_offset || base_offset & ~(~0UL >> 7))
 211                                 bad_object(obj->offset, "offset value overflow for delta base object");
 212                         p = fill(1);
 213                         c = *p;
 214                         use(1);
 215                         base_offset = (base_offset << 7) + (c & 127);
 216                 }
 217                 delta_base->offset = obj->offset - base_offset;
 218                 if (delta_base->offset >= obj->offset)
 219                         bad_object(obj->offset, "delta base offset is out of bound");
 220                 break;
 221         case OBJ_COMMIT:
 222         case OBJ_TREE:
 223         case OBJ_BLOB:
 224         case OBJ_TAG:
 225                 break;
 226         default:
 227                 bad_object(obj->offset, "bad object type %d", obj->type);
 228         }
 229         obj->hdr_size = consumed_bytes - obj->offset;
 230
 231         return unpack_entry_data(obj->offset, obj->size);
 232 }
 233
 234 static void * get_data_from_pack(struct object_entry *obj)
 235 {
 236         unsigned long from = obj[0].offset + obj[0].hdr_size;
 237         unsigned long len = obj[1].offset - from;
 238         unsigned pg_offset = from % getpagesize();
 239         unsigned char *map, *data;
 240         z_stream stream;
 241         int st;
 242
 243         map = mmap(NULL, len + pg_offset, PROT_READ, MAP_PRIVATE,
 244                    mmap_fd, from - pg_offset);
 245         if (map == MAP_FAILED)
 246                 die("cannot mmap pack file: %s", strerror(errno));
 247         data = xmalloc(obj->size);
 248         memset(&stream, 0, sizeof(stream));
 249         stream.next_out = data;
 250         stream.avail_out = obj->size;
 251         stream.next_in = map + pg_offset;
 252         stream.avail_in = len;
 253         inflateInit(&stream);
 254         while ((st = inflate(&stream, Z_FINISH)) == Z_OK);
 255         inflateEnd(&stream);
 256         if (st != Z_STREAM_END || stream.total_out != obj->size)
 257                 die("serious inflate inconsistency");
 258         munmap(map, len + pg_offset);
 259         return data;
 260 }
 261
 262 static int find_delta(const union delta_base *base)
 263 {
 264         int first = 0, last = nr_deltas;
 265
 266         while (first < last) {
 267                 int next = (first + last) / 2;
 268                 struct delta_entry *delta = &deltas[next];
 269                 int cmp;
 270
 271                 cmp = memcmp(base, &delta->base, UNION_BASE_SZ);
 272                 if (!cmp)
 273                         return next;
 274                 if (cmp < 0) {
 275                         last = next;
 276                         continue;
 277                 }
 278                 first = next+1;
 279         }
 280         return -first-1;
 281 }
 282
 283 static int find_delta_childs(const union delta_base *base,
 284                              int *first_index, int *last_index)
 285 {
 286         int first = find_delta(base);
 287         int last = first;
 288         int end = nr_deltas - 1;
 289
 290         if (first < 0)
 291                 return -1;
 292         while (first > 0 && !memcmp(&deltas[first - 1].base, base, UNION_BASE_SZ))
 293                 --first;
 294         while (last < end && !memcmp(&deltas[last + 1].base, base, UNION_BASE_SZ))
 295                 ++last;
 296         *first_index = first;
 297         *last_index = last;
 298         return 0;
 299 }
 300
 301 static void sha1_object(const void *data, unsigned long size,
 302                         enum object_type type, unsigned char *sha1)
 303 {
 304         SHA_CTX ctx;
 305         char header[50];
 306         int header_size;
 307         const char *type_str;
 308
 309         switch (type) {
 310         case OBJ_COMMIT: type_str = commit_type; break;
 311         case OBJ_TREE:   type_str = tree_type; break;
 312         case OBJ_BLOB:   type_str = blob_type; break;
 313         case OBJ_TAG:    type_str = tag_type; break;
 314         default:
 315                 die("bad type %d", type);
 316         }
 317
 318         header_size = sprintf(header, "%s %lu", type_str, size) + 1;
 319
 320         SHA1_Init(&ctx);
 321         SHA1_Update(&ctx, header, header_size);
 322         SHA1_Update(&ctx, data, size);
 323         SHA1_Final(sha1, &ctx);
 324 }
 325
 326 static void resolve_delta(struct delta_entry *delta, void *base_data,
 327                           unsigned long base_size, enum object_type type)
 328 {
 329         struct object_entry *obj = delta->obj;
 330         void *delta_data;
 331         unsigned long delta_size;
 332         void *result;
 333         unsigned long result_size;
 334         union delta_base delta_base;
 335         int j, first, last;
 336
 337         obj->real_type = type;
 338         delta_data = get_data_from_pack(obj);
 339         delta_size = obj->size;
 340         result = patch_delta(base_data, base_size, delta_data, delta_size,
 341                              &result_size);
 342         free(delta_data);
 343         if (!result)
 344                 bad_object(obj->offset, "failed to apply delta");
 345         sha1_object(result, result_size, type, obj->sha1);
 346
 347         hashcpy(delta_base.sha1, obj->sha1);
 348         if (!find_delta_childs(&delta_base, &first, &last)) {
 349                 for (j = first; j <= last; j++)
 350                         if (deltas[j].obj->type == OBJ_REF_DELTA)
 351                                 resolve_delta(&deltas[j], result, result_size, type);
 352         }
 353
 354         memset(&delta_base, 0, sizeof(delta_base));
 355         delta_base.offset = obj->offset;
 356         if (!find_delta_childs(&delta_base, &first, &last)) {
 357                 for (j = first; j <= last; j++)
 358                         if (deltas[j].obj->type == OBJ_OFS_DELTA)
 359                                 resolve_delta(&deltas[j], result, result_size, type);
 360         }
 361
 362         free(result);
 363 }
 364
 365 static int compare_delta_entry(const void *a, const void *b)
 366 {
 367         const struct delta_entry *delta_a = a;
 368         const struct delta_entry *delta_b = b;
 369         return memcmp(&delta_a->base, &delta_b->base, UNION_BASE_SZ);
 370 }
 371
 372 /* Parse all objects and return the pack content SHA1 hash */
 373 static void parse_pack_objects(unsigned char *sha1)
 374 {
 375         int i;
 376         struct delta_entry *delta = deltas;
 377         void *data;
 378         struct stat st;
 379
 380         /*
 381          * First pass:
 382          * - find locations of all objects;
 383          * - calculate SHA1 of all non-delta objects;
 384          * - remember base SHA1 for all deltas.
 385          */
 386         for (i = 0; i < nr_objects; i++) {
 387                 struct object_entry *obj = &objects[i];
 388                 data = unpack_raw_entry(obj, &delta->base);
 389                 obj->real_type = obj->type;
 390                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
 391                         nr_deltas++;
 392                         delta->obj = obj;
 393                         delta++;
 394                 } else
 395                         sha1_object(data, obj->size, obj->type, obj->sha1);
 396                 free(data);
 397         }
 398         objects[i].offset = consumed_bytes;
 399
 400         /* Check pack integrity */
 401         SHA1_Update(&input_ctx, input_buffer, input_offset);
 402         SHA1_Final(sha1, &input_ctx);
 403         if (hashcmp(fill(20), sha1))
 404                 die("pack is corrupted (SHA1 mismatch)");
 405         use(20);
 406         if (output_fd >= 0)
 407                 write_or_die(output_fd, input_buffer, input_offset);
 408
 409         /* If input_fd is a file, we should have reached its end now. */
 410         if (fstat(input_fd, &st))
 411                 die("cannot fstat packfile: %s", strerror(errno));
 412         if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes)
 413                 die("pack has junk at the end");
 414
 415         /* Sort deltas by base SHA1/offset for fast searching */
 416         qsort(deltas, nr_deltas, sizeof(struct delta_entry),
 417               compare_delta_entry);
 418
 419         /*
 420          * Second pass:
 421          * - for all non-delta objects, look if it is used as a base for
 422          *   deltas;
 423          * - if used as a base, uncompress the object and apply all deltas,
 424          *   recursively checking if the resulting object is used as a base
 425          *   for some more deltas.
 426          */
 427         for (i = 0; i < nr_objects; i++) {
 428                 struct object_entry *obj = &objects[i];
 429                 union delta_base base;
 430                 int j, ref, ref_first, ref_last, ofs, ofs_first, ofs_last;
 431
 432                 if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA)
 433                         continue;
 434                 hashcpy(base.sha1, obj->sha1);
 435                 ref = !find_delta_childs(&base, &ref_first, &ref_last);
 436                 memset(&base, 0, sizeof(base));
 437                 base.offset = obj->offset;
 438                 ofs = !find_delta_childs(&base, &ofs_first, &ofs_last);
 439                 if (!ref && !ofs)
 440                         continue;
 441                 data = get_data_from_pack(obj);
 442                 if (ref)
 443                         for (j = ref_first; j <= ref_last; j++)
 444                                 if (deltas[j].obj->type == OBJ_REF_DELTA)
 445                                         resolve_delta(&deltas[j], data,
 446                                                       obj->size, obj->type);
 447                 if (ofs)
 448                         for (j = ofs_first; j <= ofs_last; j++)
 449                                 if (deltas[j].obj->type == OBJ_OFS_DELTA)
 450                                         resolve_delta(&deltas[j], data,
 451                                                       obj->size, obj->type);
 452                 free(data);
 453         }
 454
 455         /* Check for unresolved deltas */
 456         for (i = 0; i < nr_deltas; i++) {
 457                 if (deltas[i].obj->real_type == OBJ_REF_DELTA ||
 458                     deltas[i].obj->real_type == OBJ_OFS_DELTA)
 459                         die("pack has unresolved deltas");
 460         }
 461 }
 462
 463 static int sha1_compare(const void *_a, const void *_b)
 464 {
 465         struct object_entry *a = *(struct object_entry **)_a;
 466         struct object_entry *b = *(struct object_entry **)_b;
 467         return hashcmp(a->sha1, b->sha1);
 468 }
 469
 470 /*
 471  * On entry *sha1 contains the pack content SHA1 hash, on exit it is
 472  * the SHA1 hash of sorted object names.
 473  */
 474 static const char * write_index_file(const char *index_name, unsigned char *sha1)
 475 {
 476         struct sha1file *f;
 477         struct object_entry **sorted_by_sha, **list, **last;
 478         unsigned int array[256];
 479         int i, fd;
 480         SHA_CTX ctx;
 481
 482         if (nr_objects) {
 483                 sorted_by_sha =
 484                         xcalloc(nr_objects, sizeof(struct object_entry *));
 485                 list = sorted_by_sha;
 486                 last = sorted_by_sha + nr_objects;
 487                 for (i = 0; i < nr_objects; ++i)
 488                         sorted_by_sha[i] = &objects[i];
 489                 qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
 490                       sha1_compare);
 491
 492         }
 493         else
 494                 sorted_by_sha = list = last = NULL;
 495
 496         if (!index_name) {
 497                 static char tmpfile[PATH_MAX];
 498                 snprintf(tmpfile, sizeof(tmpfile),
 499                          "%s/index_XXXXXX", get_object_directory());
 500                 fd = mkstemp(tmpfile);
 501                 index_name = xstrdup(tmpfile);
 502         } else {
 503                 unlink(index_name);
 504                 fd = open(index_name, O_CREAT|O_EXCL|O_WRONLY, 0600);
 505         }
 506         if (fd < 0)
 507                 die("unable to create %s: %s", index_name, strerror(errno));
 508         f = sha1fd(fd, index_name);
 509
 510         /*
 511          * Write the first-level table (the list is sorted,
 512          * but we use a 256-entry lookup to be able to avoid
 513          * having to do eight extra binary search iterations).
 514          */
 515         for (i = 0; i < 256; i++) {
 516                 struct object_entry **next = list;
 517                 while (next < last) {
 518                         struct object_entry *obj = *next;
 519                         if (obj->sha1[0] != i)
 520                                 break;
 521                         next++;
 522                 }
 523                 array[i] = htonl(next - sorted_by_sha);
 524                 list = next;
 525         }
 526         sha1write(f, array, 256 * sizeof(int));
 527
 528         /* recompute the SHA1 hash of sorted object names.
 529          * currently pack-objects does not do this, but that
 530          * can be fixed.
 531          */
 532         SHA1_Init(&ctx);
 533         /*
 534          * Write the actual SHA1 entries..
 535          */
 536         list = sorted_by_sha;
 537         for (i = 0; i < nr_objects; i++) {
 538                 struct object_entry *obj = *list++;
 539                 unsigned int offset = htonl(obj->offset);
 540                 sha1write(f, &offset, 4);
 541                 sha1write(f, obj->sha1, 20);
 542                 SHA1_Update(&ctx, obj->sha1, 20);
 543         }
 544         sha1write(f, sha1, 20);
 545         sha1close(f, NULL, 1);
 546         free(sorted_by_sha);
 547         SHA1_Final(sha1, &ctx);
 548         return index_name;
 549 }
 550
 551 static void final(const char *final_pack_name, const char *curr_pack_name,
 552                   const char *final_index_name, const char *curr_index_name,
 553                   unsigned char *sha1)
 554 {
 555         char name[PATH_MAX];
 556         int err;
 557
 558         if (!from_stdin) {
 559                 close(input_fd);
 560         } else {
 561                 err = close(output_fd);
 562                 if (err)
 563                         die("error while closing pack file: %s", strerror(errno));
 564                 chmod(curr_pack_name, 0444);
 565         }
 566
 567         if (final_pack_name != curr_pack_name) {
 568                 if (!final_pack_name) {
 569                         snprintf(name, sizeof(name), "%s/pack/pack-%s.pack",
 570                                  get_object_directory(), sha1_to_hex(sha1));
 571                         final_pack_name = name;
 572                 }
 573                 if (move_temp_to_file(curr_pack_name, final_pack_name))
 574                         die("cannot store pack file");
 575         }
 576
 577         chmod(curr_index_name, 0444);
 578         if (final_index_name != curr_index_name) {
 579                 if (!final_index_name) {
 580                         snprintf(name, sizeof(name), "%s/pack/pack-%s.idx",
 581                                  get_object_directory(), sha1_to_hex(sha1));
 582                         final_index_name = name;
 583                 }
 584                 if (move_temp_to_file(curr_index_name, final_index_name))
 585                         die("cannot store index file");
 586         }
 587 }
 588
 589 int main(int argc, char **argv)
 590 {
 591         int i;
 592         const char *curr_pack, *pack_name = NULL;
 593         const char *curr_index, *index_name = NULL;
 594         char *index_name_buf = NULL;
 595         unsigned char sha1[20];
 596
 597         for (i = 1; i < argc; i++) {
 598                 const char *arg = argv[i];
 599
 600                 if (*arg == '-') {
 601                         if (!strcmp(arg, "--stdin")) {
 602                                 from_stdin = 1;
 603                         } else if (!strcmp(arg, "-o")) {
 604                                 if (index_name || (i+1) >= argc)
 605                                         usage(index_pack_usage);
 606                                 index_name = argv[++i];
 607                         } else
 608                                 usage(index_pack_usage);
 609                         continue;
 610                 }
 611
 612                 if (pack_name)
 613                         usage(index_pack_usage);
 614                 pack_name = arg;
 615         }
 616
 617         if (!pack_name && !from_stdin)
 618                 usage(index_pack_usage);
 619         if (!index_name && pack_name) {
 620                 int len = strlen(pack_name);
 621                 if (!has_extension(pack_name, ".pack"))
 622                         die("packfile name '%s' does not end with '.pack'",
 623                             pack_name);
 624                 index_name_buf = xmalloc(len);
 625                 memcpy(index_name_buf, pack_name, len - 5);
 626                 strcpy(index_name_buf + len - 5, ".idx");
 627                 index_name = index_name_buf;
 628         }
 629
 630         curr_pack = open_pack_file(pack_name);
 631         parse_pack_header();
 632         objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
 633         deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
 634         parse_pack_objects(sha1);
 635         free(deltas);
 636         curr_index = write_index_file(index_name, sha1);
 637         final(pack_name, curr_pack, index_name, curr_index, sha1);
 638         free(objects);
 639         free(index_name_buf);
 640
 641         printf("%s\n", sha1_to_hex(sha1));
 642
 643         return 0;
 644 }