builtin/unpack-objects.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "config.h"
   4 #include "object-store.h"
   5 #include "object.h"
   6 #include "delta.h"
   7 #include "pack.h"
   8 #include "blob.h"
   9 #include "commit.h"
  10 #include "tag.h"
  11 #include "tree.h"
  12 #include "tree-walk.h"
  13 #include "progress.h"
  14 #include "decorate.h"
  15 #include "fsck.h"
  16
  17 static int dry_run, quiet, recover, has_errors, strict;
  18 static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict]";
  19
  20 /* We always read in 4kB chunks. */
  21 static unsigned char buffer[4096];
  22 static unsigned int offset, len;
  23 static off_t consumed_bytes;
  24 static off_t max_input_size;
  25 static git_hash_ctx ctx;
  26 static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
  27
  28 /*
  29  * When running under --strict mode, objects whose reachability are
  30  * suspect are kept in core without getting written in the object
  31  * store.
  32  */
  33 struct obj_buffer {
  34         char *buffer;
  35         unsigned long size;
  36 };
  37
  38 static struct decoration obj_decorate;
  39
  40 static struct obj_buffer *lookup_object_buffer(struct object *base)
  41 {
  42         return lookup_decoration(&obj_decorate, base);
  43 }
  44
  45 static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
  46 {
  47         struct obj_buffer *obj;
  48         obj = xcalloc(1, sizeof(struct obj_buffer));
  49         obj->buffer = buffer;
  50         obj->size = size;
  51         if (add_decoration(&obj_decorate, object, obj))
  52                 die("object %s tried to add buffer twice!", oid_to_hex(&object->oid));
  53 }
  54
  55 /*
  56  * Make sure at least "min" bytes are available in the buffer, and
  57  * return the pointer to the buffer.
  58  */
  59 static void *fill(int min)
  60 {
  61         if (min <= len)
  62                 return buffer + offset;
  63         if (min > sizeof(buffer))
  64                 die("cannot fill %d bytes", min);
  65         if (offset) {
  66                 the_hash_algo->update_fn(&ctx, buffer, offset);
  67                 memmove(buffer, buffer + offset, len);
  68                 offset = 0;
  69         }
  70         do {
  71                 ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
  72                 if (ret <= 0) {
  73                         if (!ret)
  74                                 die("early EOF");
  75                         die_errno("read error on input");
  76                 }
  77                 len += ret;
  78         } while (len < min);
  79         return buffer;
  80 }
  81
  82 static void use(int bytes)
  83 {
  84         if (bytes > len)
  85                 die("used more bytes than were available");
  86         len -= bytes;
  87         offset += bytes;
  88
  89         /* make sure off_t is sufficiently large not to wrap */
  90         if (signed_add_overflows(consumed_bytes, bytes))
  91                 die("pack too large for current definition of off_t");
  92         consumed_bytes += bytes;
  93         if (max_input_size && consumed_bytes > max_input_size)
  94                 die(_("pack exceeds maximum allowed size"));
  95 }
  96
  97 static void *get_data(unsigned long size)
  98 {
  99         git_zstream stream;
 100         void *buf = xmallocz(size);
 101
 102         memset(&stream, 0, sizeof(stream));
 103
 104         stream.next_out = buf;
 105         stream.avail_out = size;
 106         stream.next_in = fill(1);
 107         stream.avail_in = len;
 108         git_inflate_init(&stream);
 109
 110         for (;;) {
 111                 int ret = git_inflate(&stream, 0);
 112                 use(len - stream.avail_in);
 113                 if (stream.total_out == size && ret == Z_STREAM_END)
 114                         break;
 115                 if (ret != Z_OK) {
 116                         error("inflate returned %d", ret);
 117                         FREE_AND_NULL(buf);
 118                         if (!recover)
 119                                 exit(1);
 120                         has_errors = 1;
 121                         break;
 122                 }
 123                 stream.next_in = fill(1);
 124                 stream.avail_in = len;
 125         }
 126         git_inflate_end(&stream);
 127         return buf;
 128 }
 129
 130 struct delta_info {
 131         struct object_id base_oid;
 132         unsigned nr;
 133         off_t base_offset;
 134         unsigned long size;
 135         void *delta;
 136         struct delta_info *next;
 137 };
 138
 139 static struct delta_info *delta_list;
 140
 141 static void add_delta_to_list(unsigned nr, const struct object_id *base_oid,
 142                               off_t base_offset,
 143                               void *delta, unsigned long size)
 144 {
 145         struct delta_info *info = xmalloc(sizeof(*info));
 146
 147         oidcpy(&info->base_oid, base_oid);
 148         info->base_offset = base_offset;
 149         info->size = size;
 150         info->delta = delta;
 151         info->nr = nr;
 152         info->next = delta_list;
 153         delta_list = info;
 154 }
 155
 156 struct obj_info {
 157         off_t offset;
 158         struct object_id oid;
 159         struct object *obj;
 160 };
 161
 162 /* Remember to update object flag allocation in object.h */
 163 #define FLAG_OPEN (1u<<20)
 164 #define FLAG_WRITTEN (1u<<21)
 165
 166 static struct obj_info *obj_list;
 167 static unsigned nr_objects;
 168
 169 /*
 170  * Called only from check_object() after it verified this object
 171  * is Ok.
 172  */
 173 static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 174 {
 175         struct object_id oid;
 176
 177         if (write_object_file(obj_buf->buffer, obj_buf->size,
 178                               type_name(obj->type), &oid) < 0)
 179                 die("failed to write object %s", oid_to_hex(&obj->oid));
 180         obj->flags |= FLAG_WRITTEN;
 181 }
 182
 183 /*
 184  * At the very end of the processing, write_rest() scans the objects
 185  * that have reachability requirements and calls this function.
 186  * Verify its reachability and validity recursively and write it out.
 187  */
 188 static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 189 {
 190         struct obj_buffer *obj_buf;
 191
 192         if (!obj)
 193                 return 1;
 194
 195         if (obj->flags & FLAG_WRITTEN)
 196                 return 0;
 197
 198         if (type != OBJ_ANY && obj->type != type)
 199                 die("object type mismatch");
 200
 201         if (!(obj->flags & FLAG_OPEN)) {
 202                 unsigned long size;
 203                 int type = oid_object_info(the_repository, &obj->oid, &size);
 204                 if (type != obj->type || type <= 0)
 205                         die("object of unexpected type");
 206                 obj->flags |= FLAG_WRITTEN;
 207                 return 0;
 208         }
 209
 210         obj_buf = lookup_object_buffer(obj);
 211         if (!obj_buf)
 212                 die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
 213         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 214                 die("fsck error in packed object");
 215         fsck_options.walk = check_object;
 216         if (fsck_walk(obj, NULL, &fsck_options))
 217                 die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
 218         write_cached_object(obj, obj_buf);
 219         return 0;
 220 }
 221
 222 static void write_rest(void)
 223 {
 224         unsigned i;
 225         for (i = 0; i < nr_objects; i++) {
 226                 if (obj_list[i].obj)
 227                         check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 228         }
 229 }
 230
 231 static void added_object(unsigned nr, enum object_type type,
 232                          void *data, unsigned long size);
 233
 234 /*
 235  * Write out nr-th object from the list, now we know the contents
 236  * of it.  Under --strict, this buffers structured objects in-core,
 237  * to be checked at the end.
 238  */
 239 static void write_object(unsigned nr, enum object_type type,
 240                          void *buf, unsigned long size)
 241 {
 242         if (!strict) {
 243                 if (write_object_file(buf, size, type_name(type),
 244                                       &obj_list[nr].oid) < 0)
 245                         die("failed to write object");
 246                 added_object(nr, type, buf, size);
 247                 free(buf);
 248                 obj_list[nr].obj = NULL;
 249         } else if (type == OBJ_BLOB) {
 250                 struct blob *blob;
 251                 if (write_object_file(buf, size, type_name(type),
 252                                       &obj_list[nr].oid) < 0)
 253                         die("failed to write object");
 254                 added_object(nr, type, buf, size);
 255                 free(buf);
 256
 257                 blob = lookup_blob(&obj_list[nr].oid);
 258                 if (blob)
 259                         blob->object.flags |= FLAG_WRITTEN;
 260                 else
 261                         die("invalid blob object");
 262                 obj_list[nr].obj = NULL;
 263         } else {
 264                 struct object *obj;
 265                 int eaten;
 266                 hash_object_file(buf, size, type_name(type), &obj_list[nr].oid);
 267                 added_object(nr, type, buf, size);
 268                 obj = parse_object_buffer(&obj_list[nr].oid, type, size, buf,
 269                                           &eaten);
 270                 if (!obj)
 271                         die("invalid %s", type_name(type));
 272                 add_object_buffer(obj, buf, size);
 273                 obj->flags |= FLAG_OPEN;
 274                 obj_list[nr].obj = obj;
 275         }
 276 }
 277
 278 static void resolve_delta(unsigned nr, enum object_type type,
 279                           void *base, unsigned long base_size,
 280                           void *delta, unsigned long delta_size)
 281 {
 282         void *result;
 283         unsigned long result_size;
 284
 285         result = patch_delta(base, base_size,
 286                              delta, delta_size,
 287                              &result_size);
 288         if (!result)
 289                 die("failed to apply delta");
 290         free(delta);
 291         write_object(nr, type, result, result_size);
 292 }
 293
 294 /*
 295  * We now know the contents of an object (which is nr-th in the pack);
 296  * resolve all the deltified objects that are based on it.
 297  */
 298 static void added_object(unsigned nr, enum object_type type,
 299                          void *data, unsigned long size)
 300 {
 301         struct delta_info **p = &delta_list;
 302         struct delta_info *info;
 303
 304         while ((info = *p) != NULL) {
 305                 if (!oidcmp(&info->base_oid, &obj_list[nr].oid) ||
 306                     info->base_offset == obj_list[nr].offset) {
 307                         *p = info->next;
 308                         p = &delta_list;
 309                         resolve_delta(info->nr, type, data, size,
 310                                       info->delta, info->size);
 311                         free(info);
 312                         continue;
 313                 }
 314                 p = &info->next;
 315         }
 316 }
 317
 318 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 319                                    unsigned nr)
 320 {
 321         void *buf = get_data(size);
 322
 323         if (!dry_run && buf)
 324                 write_object(nr, type, buf, size);
 325         else
 326                 free(buf);
 327 }
 328
 329 static int resolve_against_held(unsigned nr, const struct object_id *base,
 330                                 void *delta_data, unsigned long delta_size)
 331 {
 332         struct object *obj;
 333         struct obj_buffer *obj_buffer;
 334         obj = lookup_object(base->hash);
 335         if (!obj)
 336                 return 0;
 337         obj_buffer = lookup_object_buffer(obj);
 338         if (!obj_buffer)
 339                 return 0;
 340         resolve_delta(nr, obj->type, obj_buffer->buffer,
 341                       obj_buffer->size, delta_data, delta_size);
 342         return 1;
 343 }
 344
 345 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 346                                unsigned nr)
 347 {
 348         void *delta_data, *base;
 349         unsigned long base_size;
 350         struct object_id base_oid;
 351
 352         if (type == OBJ_REF_DELTA) {
 353                 hashcpy(base_oid.hash, fill(the_hash_algo->rawsz));
 354                 use(the_hash_algo->rawsz);
 355                 delta_data = get_data(delta_size);
 356                 if (dry_run || !delta_data) {
 357                         free(delta_data);
 358                         return;
 359                 }
 360                 if (has_object_file(&base_oid))
 361                         ; /* Ok we have this one */
 362                 else if (resolve_against_held(nr, &base_oid,
 363                                               delta_data, delta_size))
 364                         return; /* we are done */
 365                 else {
 366                         /* cannot resolve yet --- queue it */
 367                         oidclr(&obj_list[nr].oid);
 368                         add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
 369                         return;
 370                 }
 371         } else {
 372                 unsigned base_found = 0;
 373                 unsigned char *pack, c;
 374                 off_t base_offset;
 375                 unsigned lo, mid, hi;
 376
 377                 pack = fill(1);
 378                 c = *pack;
 379                 use(1);
 380                 base_offset = c & 127;
 381                 while (c & 128) {
 382                         base_offset += 1;
 383                         if (!base_offset || MSB(base_offset, 7))
 384                                 die("offset value overflow for delta base object");
 385                         pack = fill(1);
 386                         c = *pack;
 387                         use(1);
 388                         base_offset = (base_offset << 7) + (c & 127);
 389                 }
 390                 base_offset = obj_list[nr].offset - base_offset;
 391                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 392                         die("offset value out of bound for delta base object");
 393
 394                 delta_data = get_data(delta_size);
 395                 if (dry_run || !delta_data) {
 396                         free(delta_data);
 397                         return;
 398                 }
 399                 lo = 0;
 400                 hi = nr;
 401                 while (lo < hi) {
 402                         mid = lo + (hi - lo) / 2;
 403                         if (base_offset < obj_list[mid].offset) {
 404                                 hi = mid;
 405                         } else if (base_offset > obj_list[mid].offset) {
 406                                 lo = mid + 1;
 407                         } else {
 408                                 oidcpy(&base_oid, &obj_list[mid].oid);
 409                                 base_found = !is_null_oid(&base_oid);
 410                                 break;
 411                         }
 412                 }
 413                 if (!base_found) {
 414                         /*
 415                          * The delta base object is itself a delta that
 416                          * has not been resolved yet.
 417                          */
 418                         oidclr(&obj_list[nr].oid);
 419                         add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
 420                         return;
 421                 }
 422         }
 423
 424         if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 425                 return;
 426
 427         base = read_object_file(&base_oid, &type, &base_size);
 428         if (!base) {
 429                 error("failed to read delta-pack base object %s",
 430                       oid_to_hex(&base_oid));
 431                 if (!recover)
 432                         exit(1);
 433                 has_errors = 1;
 434                 return;
 435         }
 436         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 437         free(base);
 438 }
 439
 440 static void unpack_one(unsigned nr)
 441 {
 442         unsigned shift;
 443         unsigned char *pack;
 444         unsigned long size, c;
 445         enum object_type type;
 446
 447         obj_list[nr].offset = consumed_bytes;
 448
 449         pack = fill(1);
 450         c = *pack;
 451         use(1);
 452         type = (c >> 4) & 7;
 453         size = (c & 15);
 454         shift = 4;
 455         while (c & 0x80) {
 456                 pack = fill(1);
 457                 c = *pack;
 458                 use(1);
 459                 size += (c & 0x7f) << shift;
 460                 shift += 7;
 461         }
 462
 463         switch (type) {
 464         case OBJ_COMMIT:
 465         case OBJ_TREE:
 466         case OBJ_BLOB:
 467         case OBJ_TAG:
 468                 unpack_non_delta_entry(type, size, nr);
 469                 return;
 470         case OBJ_REF_DELTA:
 471         case OBJ_OFS_DELTA:
 472                 unpack_delta_entry(type, size, nr);
 473                 return;
 474         default:
 475                 error("bad object type %d", type);
 476                 has_errors = 1;
 477                 if (recover)
 478                         return;
 479                 exit(1);
 480         }
 481 }
 482
 483 static void unpack_all(void)
 484 {
 485         int i;
 486         struct progress *progress = NULL;
 487         struct pack_header *hdr = fill(sizeof(struct pack_header));
 488
 489         nr_objects = ntohl(hdr->hdr_entries);
 490
 491         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 492                 die("bad pack file");
 493         if (!pack_version_ok(hdr->hdr_version))
 494                 die("unknown pack file version %"PRIu32,
 495                         ntohl(hdr->hdr_version));
 496         use(sizeof(struct pack_header));
 497
 498         if (!quiet)
 499                 progress = start_progress(_("Unpacking objects"), nr_objects);
 500         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 501         for (i = 0; i < nr_objects; i++) {
 502                 unpack_one(i);
 503                 display_progress(progress, i + 1);
 504         }
 505         stop_progress(&progress);
 506
 507         if (delta_list)
 508                 die("unresolved deltas left after unpacking");
 509 }
 510
 511 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 512 {
 513         int i;
 514         struct object_id oid;
 515
 516         check_replace_refs = 0;
 517
 518         git_config(git_default_config, NULL);
 519
 520         quiet = !isatty(2);
 521
 522         for (i = 1 ; i < argc; i++) {
 523                 const char *arg = argv[i];
 524
 525                 if (*arg == '-') {
 526                         if (!strcmp(arg, "-n")) {
 527                                 dry_run = 1;
 528                                 continue;
 529                         }
 530                         if (!strcmp(arg, "-q")) {
 531                                 quiet = 1;
 532                                 continue;
 533                         }
 534                         if (!strcmp(arg, "-r")) {
 535                                 recover = 1;
 536                                 continue;
 537                         }
 538                         if (!strcmp(arg, "--strict")) {
 539                                 strict = 1;
 540                                 continue;
 541                         }
 542                         if (skip_prefix(arg, "--strict=", &arg)) {
 543                                 strict = 1;
 544                                 fsck_set_msg_types(&fsck_options, arg);
 545                                 continue;
 546                         }
 547                         if (starts_with(arg, "--pack_header=")) {
 548                                 struct pack_header *hdr;
 549                                 char *c;
 550
 551                                 hdr = (struct pack_header *)buffer;
 552                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 553                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 554                                 if (*c != ',')
 555                                         die("bad %s", arg);
 556                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 557                                 if (*c)
 558                                         die("bad %s", arg);
 559                                 len = sizeof(*hdr);
 560                                 continue;
 561                         }
 562                         if (skip_prefix(arg, "--max-input-size=", &arg)) {
 563                                 max_input_size = strtoumax(arg, NULL, 10);
 564                                 continue;
 565                         }
 566                         usage(unpack_usage);
 567                 }
 568
 569                 /* We don't take any non-flag arguments now.. Maybe some day */
 570                 usage(unpack_usage);
 571         }
 572         the_hash_algo->init_fn(&ctx);
 573         unpack_all();
 574         the_hash_algo->update_fn(&ctx, buffer, offset);
 575         the_hash_algo->final_fn(oid.hash, &ctx);
 576         if (strict) {
 577                 write_rest();
 578                 if (fsck_finish(&fsck_options))
 579                         die(_("fsck error in pack objects"));
 580         }
 581         if (hashcmp(fill(the_hash_algo->rawsz), oid.hash))
 582                 die("final sha1 did not match");
 583         use(the_hash_algo->rawsz);
 584
 585         /* Write the last part of the buffer to stdout */
 586         while (len) {
 587                 int ret = xwrite(1, buffer + offset, len);
 588                 if (ret <= 0)
 589                         break;
 590                 len -= ret;
 591                 offset += ret;
 592         }
 593
 594         /* All done */
 595         return has_errors;
 596 }