builtin/unpack-objects.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "object.h"
   5 #include "delta.h"
   6 #include "pack.h"
   7 #include "blob.h"
   8 #include "commit.h"
   9 #include "tag.h"
  10 #include "tree.h"
  11 #include "tree-walk.h"
  12 #include "progress.h"
  13 #include "decorate.h"
  14 #include "fsck.h"
  15
  16 static int dry_run, quiet, recover, has_errors, strict;
  17 static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict]";
  18
  19 /* We always read in 4kB chunks. */
  20 static unsigned char buffer[4096];
  21 static unsigned int offset, len;
  22 static off_t consumed_bytes;
  23 static off_t max_input_size;
  24 static git_hash_ctx ctx;
  25 static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
  26
  27 /*
  28  * When running under --strict mode, objects whose reachability are
  29  * suspect are kept in core without getting written in the object
  30  * store.
  31  */
  32 struct obj_buffer {
  33         char *buffer;
  34         unsigned long size;
  35 };
  36
  37 static struct decoration obj_decorate;
  38
  39 static struct obj_buffer *lookup_object_buffer(struct object *base)
  40 {
  41         return lookup_decoration(&obj_decorate, base);
  42 }
  43
  44 static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
  45 {
  46         struct obj_buffer *obj;
  47         obj = xcalloc(1, sizeof(struct obj_buffer));
  48         obj->buffer = buffer;
  49         obj->size = size;
  50         if (add_decoration(&obj_decorate, object, obj))
  51                 die("object %s tried to add buffer twice!", oid_to_hex(&object->oid));
  52 }
  53
  54 /*
  55  * Make sure at least "min" bytes are available in the buffer, and
  56  * return the pointer to the buffer.
  57  */
  58 static void *fill(int min)
  59 {
  60         if (min <= len)
  61                 return buffer + offset;
  62         if (min > sizeof(buffer))
  63                 die("cannot fill %d bytes", min);
  64         if (offset) {
  65                 the_hash_algo->update_fn(&ctx, buffer, offset);
  66                 memmove(buffer, buffer + offset, len);
  67                 offset = 0;
  68         }
  69         do {
  70                 ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
  71                 if (ret <= 0) {
  72                         if (!ret)
  73                                 die("early EOF");
  74                         die_errno("read error on input");
  75                 }
  76                 len += ret;
  77         } while (len < min);
  78         return buffer;
  79 }
  80
  81 static void use(int bytes)
  82 {
  83         if (bytes > len)
  84                 die("used more bytes than were available");
  85         len -= bytes;
  86         offset += bytes;
  87
  88         /* make sure off_t is sufficiently large not to wrap */
  89         if (signed_add_overflows(consumed_bytes, bytes))
  90                 die("pack too large for current definition of off_t");
  91         consumed_bytes += bytes;
  92         if (max_input_size && consumed_bytes > max_input_size)
  93                 die(_("pack exceeds maximum allowed size"));
  94 }
  95
  96 static void *get_data(unsigned long size)
  97 {
  98         git_zstream stream;
  99         void *buf = xmallocz(size);
 100
 101         memset(&stream, 0, sizeof(stream));
 102
 103         stream.next_out = buf;
 104         stream.avail_out = size;
 105         stream.next_in = fill(1);
 106         stream.avail_in = len;
 107         git_inflate_init(&stream);
 108
 109         for (;;) {
 110                 int ret = git_inflate(&stream, 0);
 111                 use(len - stream.avail_in);
 112                 if (stream.total_out == size && ret == Z_STREAM_END)
 113                         break;
 114                 if (ret != Z_OK) {
 115                         error("inflate returned %d", ret);
 116                         FREE_AND_NULL(buf);
 117                         if (!recover)
 118                                 exit(1);
 119                         has_errors = 1;
 120                         break;
 121                 }
 122                 stream.next_in = fill(1);
 123                 stream.avail_in = len;
 124         }
 125         git_inflate_end(&stream);
 126         return buf;
 127 }
 128
 129 struct delta_info {
 130         struct object_id base_oid;
 131         unsigned nr;
 132         off_t base_offset;
 133         unsigned long size;
 134         void *delta;
 135         struct delta_info *next;
 136 };
 137
 138 static struct delta_info *delta_list;
 139
 140 static void add_delta_to_list(unsigned nr, const struct object_id *base_oid,
 141                               off_t base_offset,
 142                               void *delta, unsigned long size)
 143 {
 144         struct delta_info *info = xmalloc(sizeof(*info));
 145
 146         oidcpy(&info->base_oid, base_oid);
 147         info->base_offset = base_offset;
 148         info->size = size;
 149         info->delta = delta;
 150         info->nr = nr;
 151         info->next = delta_list;
 152         delta_list = info;
 153 }
 154
 155 struct obj_info {
 156         off_t offset;
 157         struct object_id oid;
 158         struct object *obj;
 159 };
 160
 161 /* Remember to update object flag allocation in object.h */
 162 #define FLAG_OPEN (1u<<20)
 163 #define FLAG_WRITTEN (1u<<21)
 164
 165 static struct obj_info *obj_list;
 166 static unsigned nr_objects;
 167
 168 /*
 169  * Called only from check_object() after it verified this object
 170  * is Ok.
 171  */
 172 static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 173 {
 174         struct object_id oid;
 175
 176         if (write_object_file(obj_buf->buffer, obj_buf->size,
 177                               type_name(obj->type), &oid) < 0)
 178                 die("failed to write object %s", oid_to_hex(&obj->oid));
 179         obj->flags |= FLAG_WRITTEN;
 180 }
 181
 182 /*
 183  * At the very end of the processing, write_rest() scans the objects
 184  * that have reachability requirements and calls this function.
 185  * Verify its reachability and validity recursively and write it out.
 186  */
 187 static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 188 {
 189         struct obj_buffer *obj_buf;
 190
 191         if (!obj)
 192                 return 1;
 193
 194         if (obj->flags & FLAG_WRITTEN)
 195                 return 0;
 196
 197         if (type != OBJ_ANY && obj->type != type)
 198                 die("object type mismatch");
 199
 200         if (!(obj->flags & FLAG_OPEN)) {
 201                 unsigned long size;
 202                 int type = oid_object_info(the_repository, &obj->oid, &size);
 203                 if (type != obj->type || type <= 0)
 204                         die("object of unexpected type");
 205                 obj->flags |= FLAG_WRITTEN;
 206                 return 0;
 207         }
 208
 209         obj_buf = lookup_object_buffer(obj);
 210         if (!obj_buf)
 211                 die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
 212         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 213                 die("fsck error in packed object");
 214         fsck_options.walk = check_object;
 215         if (fsck_walk(obj, NULL, &fsck_options))
 216                 die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
 217         write_cached_object(obj, obj_buf);
 218         return 0;
 219 }
 220
 221 static void write_rest(void)
 222 {
 223         unsigned i;
 224         for (i = 0; i < nr_objects; i++) {
 225                 if (obj_list[i].obj)
 226                         check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 227         }
 228 }
 229
 230 static void added_object(unsigned nr, enum object_type type,
 231                          void *data, unsigned long size);
 232
 233 /*
 234  * Write out nr-th object from the list, now we know the contents
 235  * of it.  Under --strict, this buffers structured objects in-core,
 236  * to be checked at the end.
 237  */
 238 static void write_object(unsigned nr, enum object_type type,
 239                          void *buf, unsigned long size)
 240 {
 241         if (!strict) {
 242                 if (write_object_file(buf, size, type_name(type),
 243                                       &obj_list[nr].oid) < 0)
 244                         die("failed to write object");
 245                 added_object(nr, type, buf, size);
 246                 free(buf);
 247                 obj_list[nr].obj = NULL;
 248         } else if (type == OBJ_BLOB) {
 249                 struct blob *blob;
 250                 if (write_object_file(buf, size, type_name(type),
 251                                       &obj_list[nr].oid) < 0)
 252                         die("failed to write object");
 253                 added_object(nr, type, buf, size);
 254                 free(buf);
 255
 256                 blob = lookup_blob(&obj_list[nr].oid);
 257                 if (blob)
 258                         blob->object.flags |= FLAG_WRITTEN;
 259                 else
 260                         die("invalid blob object");
 261                 obj_list[nr].obj = NULL;
 262         } else {
 263                 struct object *obj;
 264                 int eaten;
 265                 hash_object_file(buf, size, type_name(type), &obj_list[nr].oid);
 266                 added_object(nr, type, buf, size);
 267                 obj = parse_object_buffer(&obj_list[nr].oid, type, size, buf,
 268                                           &eaten);
 269                 if (!obj)
 270                         die("invalid %s", type_name(type));
 271                 add_object_buffer(obj, buf, size);
 272                 obj->flags |= FLAG_OPEN;
 273                 obj_list[nr].obj = obj;
 274         }
 275 }
 276
 277 static void resolve_delta(unsigned nr, enum object_type type,
 278                           void *base, unsigned long base_size,
 279                           void *delta, unsigned long delta_size)
 280 {
 281         void *result;
 282         unsigned long result_size;
 283
 284         result = patch_delta(base, base_size,
 285                              delta, delta_size,
 286                              &result_size);
 287         if (!result)
 288                 die("failed to apply delta");
 289         free(delta);
 290         write_object(nr, type, result, result_size);
 291 }
 292
 293 /*
 294  * We now know the contents of an object (which is nr-th in the pack);
 295  * resolve all the deltified objects that are based on it.
 296  */
 297 static void added_object(unsigned nr, enum object_type type,
 298                          void *data, unsigned long size)
 299 {
 300         struct delta_info **p = &delta_list;
 301         struct delta_info *info;
 302
 303         while ((info = *p) != NULL) {
 304                 if (!oidcmp(&info->base_oid, &obj_list[nr].oid) ||
 305                     info->base_offset == obj_list[nr].offset) {
 306                         *p = info->next;
 307                         p = &delta_list;
 308                         resolve_delta(info->nr, type, data, size,
 309                                       info->delta, info->size);
 310                         free(info);
 311                         continue;
 312                 }
 313                 p = &info->next;
 314         }
 315 }
 316
 317 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 318                                    unsigned nr)
 319 {
 320         void *buf = get_data(size);
 321
 322         if (!dry_run && buf)
 323                 write_object(nr, type, buf, size);
 324         else
 325                 free(buf);
 326 }
 327
 328 static int resolve_against_held(unsigned nr, const struct object_id *base,
 329                                 void *delta_data, unsigned long delta_size)
 330 {
 331         struct object *obj;
 332         struct obj_buffer *obj_buffer;
 333         obj = lookup_object(base->hash);
 334         if (!obj)
 335                 return 0;
 336         obj_buffer = lookup_object_buffer(obj);
 337         if (!obj_buffer)
 338                 return 0;
 339         resolve_delta(nr, obj->type, obj_buffer->buffer,
 340                       obj_buffer->size, delta_data, delta_size);
 341         return 1;
 342 }
 343
 344 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 345                                unsigned nr)
 346 {
 347         void *delta_data, *base;
 348         unsigned long base_size;
 349         struct object_id base_oid;
 350
 351         if (type == OBJ_REF_DELTA) {
 352                 hashcpy(base_oid.hash, fill(the_hash_algo->rawsz));
 353                 use(the_hash_algo->rawsz);
 354                 delta_data = get_data(delta_size);
 355                 if (dry_run || !delta_data) {
 356                         free(delta_data);
 357                         return;
 358                 }
 359                 if (has_object_file(&base_oid))
 360                         ; /* Ok we have this one */
 361                 else if (resolve_against_held(nr, &base_oid,
 362                                               delta_data, delta_size))
 363                         return; /* we are done */
 364                 else {
 365                         /* cannot resolve yet --- queue it */
 366                         oidclr(&obj_list[nr].oid);
 367                         add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
 368                         return;
 369                 }
 370         } else {
 371                 unsigned base_found = 0;
 372                 unsigned char *pack, c;
 373                 off_t base_offset;
 374                 unsigned lo, mid, hi;
 375
 376                 pack = fill(1);
 377                 c = *pack;
 378                 use(1);
 379                 base_offset = c & 127;
 380                 while (c & 128) {
 381                         base_offset += 1;
 382                         if (!base_offset || MSB(base_offset, 7))
 383                                 die("offset value overflow for delta base object");
 384                         pack = fill(1);
 385                         c = *pack;
 386                         use(1);
 387                         base_offset = (base_offset << 7) + (c & 127);
 388                 }
 389                 base_offset = obj_list[nr].offset - base_offset;
 390                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 391                         die("offset value out of bound for delta base object");
 392
 393                 delta_data = get_data(delta_size);
 394                 if (dry_run || !delta_data) {
 395                         free(delta_data);
 396                         return;
 397                 }
 398                 lo = 0;
 399                 hi = nr;
 400                 while (lo < hi) {
 401                         mid = lo + (hi - lo) / 2;
 402                         if (base_offset < obj_list[mid].offset) {
 403                                 hi = mid;
 404                         } else if (base_offset > obj_list[mid].offset) {
 405                                 lo = mid + 1;
 406                         } else {
 407                                 oidcpy(&base_oid, &obj_list[mid].oid);
 408                                 base_found = !is_null_oid(&base_oid);
 409                                 break;
 410                         }
 411                 }
 412                 if (!base_found) {
 413                         /*
 414                          * The delta base object is itself a delta that
 415                          * has not been resolved yet.
 416                          */
 417                         oidclr(&obj_list[nr].oid);
 418                         add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
 419                         return;
 420                 }
 421         }
 422
 423         if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 424                 return;
 425
 426         base = read_object_file(&base_oid, &type, &base_size);
 427         if (!base) {
 428                 error("failed to read delta-pack base object %s",
 429                       oid_to_hex(&base_oid));
 430                 if (!recover)
 431                         exit(1);
 432                 has_errors = 1;
 433                 return;
 434         }
 435         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 436         free(base);
 437 }
 438
 439 static void unpack_one(unsigned nr)
 440 {
 441         unsigned shift;
 442         unsigned char *pack;
 443         unsigned long size, c;
 444         enum object_type type;
 445
 446         obj_list[nr].offset = consumed_bytes;
 447
 448         pack = fill(1);
 449         c = *pack;
 450         use(1);
 451         type = (c >> 4) & 7;
 452         size = (c & 15);
 453         shift = 4;
 454         while (c & 0x80) {
 455                 pack = fill(1);
 456                 c = *pack;
 457                 use(1);
 458                 size += (c & 0x7f) << shift;
 459                 shift += 7;
 460         }
 461
 462         switch (type) {
 463         case OBJ_COMMIT:
 464         case OBJ_TREE:
 465         case OBJ_BLOB:
 466         case OBJ_TAG:
 467                 unpack_non_delta_entry(type, size, nr);
 468                 return;
 469         case OBJ_REF_DELTA:
 470         case OBJ_OFS_DELTA:
 471                 unpack_delta_entry(type, size, nr);
 472                 return;
 473         default:
 474                 error("bad object type %d", type);
 475                 has_errors = 1;
 476                 if (recover)
 477                         return;
 478                 exit(1);
 479         }
 480 }
 481
 482 static void unpack_all(void)
 483 {
 484         int i;
 485         struct progress *progress = NULL;
 486         struct pack_header *hdr = fill(sizeof(struct pack_header));
 487
 488         nr_objects = ntohl(hdr->hdr_entries);
 489
 490         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 491                 die("bad pack file");
 492         if (!pack_version_ok(hdr->hdr_version))
 493                 die("unknown pack file version %"PRIu32,
 494                         ntohl(hdr->hdr_version));
 495         use(sizeof(struct pack_header));
 496
 497         if (!quiet)
 498                 progress = start_progress(_("Unpacking objects"), nr_objects);
 499         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 500         for (i = 0; i < nr_objects; i++) {
 501                 unpack_one(i);
 502                 display_progress(progress, i + 1);
 503         }
 504         stop_progress(&progress);
 505
 506         if (delta_list)
 507                 die("unresolved deltas left after unpacking");
 508 }
 509
 510 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 511 {
 512         int i;
 513         struct object_id oid;
 514
 515         check_replace_refs = 0;
 516
 517         git_config(git_default_config, NULL);
 518
 519         quiet = !isatty(2);
 520
 521         for (i = 1 ; i < argc; i++) {
 522                 const char *arg = argv[i];
 523
 524                 if (*arg == '-') {
 525                         if (!strcmp(arg, "-n")) {
 526                                 dry_run = 1;
 527                                 continue;
 528                         }
 529                         if (!strcmp(arg, "-q")) {
 530                                 quiet = 1;
 531                                 continue;
 532                         }
 533                         if (!strcmp(arg, "-r")) {
 534                                 recover = 1;
 535                                 continue;
 536                         }
 537                         if (!strcmp(arg, "--strict")) {
 538                                 strict = 1;
 539                                 continue;
 540                         }
 541                         if (skip_prefix(arg, "--strict=", &arg)) {
 542                                 strict = 1;
 543                                 fsck_set_msg_types(&fsck_options, arg);
 544                                 continue;
 545                         }
 546                         if (starts_with(arg, "--pack_header=")) {
 547                                 struct pack_header *hdr;
 548                                 char *c;
 549
 550                                 hdr = (struct pack_header *)buffer;
 551                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 552                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 553                                 if (*c != ',')
 554                                         die("bad %s", arg);
 555                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 556                                 if (*c)
 557                                         die("bad %s", arg);
 558                                 len = sizeof(*hdr);
 559                                 continue;
 560                         }
 561                         if (skip_prefix(arg, "--max-input-size=", &arg)) {
 562                                 max_input_size = strtoumax(arg, NULL, 10);
 563                                 continue;
 564                         }
 565                         usage(unpack_usage);
 566                 }
 567
 568                 /* We don't take any non-flag arguments now.. Maybe some day */
 569                 usage(unpack_usage);
 570         }
 571         the_hash_algo->init_fn(&ctx);
 572         unpack_all();
 573         the_hash_algo->update_fn(&ctx, buffer, offset);
 574         the_hash_algo->final_fn(oid.hash, &ctx);
 575         if (strict) {
 576                 write_rest();
 577                 if (fsck_finish(&fsck_options))
 578                         die(_("fsck error in pack objects"));
 579         }
 580         if (hashcmp(fill(the_hash_algo->rawsz), oid.hash))
 581                 die("final sha1 did not match");
 582         use(the_hash_algo->rawsz);
 583
 584         /* Write the last part of the buffer to stdout */
 585         while (len) {
 586                 int ret = xwrite(1, buffer + offset, len);
 587                 if (ret <= 0)
 588                         break;
 589                 len -= ret;
 590                 offset += ret;
 591         }
 592
 593         /* All done */
 594         return has_errors;
 595 }