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 #define FLAG_OPEN (1u<<20)
 162 #define FLAG_WRITTEN (1u<<21)
 163
 164 static struct obj_info *obj_list;
 165 static unsigned nr_objects;
 166
 167 /*
 168  * Called only from check_object() after it verified this object
 169  * is Ok.
 170  */
 171 static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 172 {
 173         struct object_id oid;
 174
 175         if (write_object_file(obj_buf->buffer, obj_buf->size,
 176                               type_name(obj->type), &oid) < 0)
 177                 die("failed to write object %s", oid_to_hex(&obj->oid));
 178         obj->flags |= FLAG_WRITTEN;
 179 }
 180
 181 /*
 182  * At the very end of the processing, write_rest() scans the objects
 183  * that have reachability requirements and calls this function.
 184  * Verify its reachability and validity recursively and write it out.
 185  */
 186 static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 187 {
 188         struct obj_buffer *obj_buf;
 189
 190         if (!obj)
 191                 return 1;
 192
 193         if (obj->flags & FLAG_WRITTEN)
 194                 return 0;
 195
 196         if (type != OBJ_ANY && obj->type != type)
 197                 die("object type mismatch");
 198
 199         if (!(obj->flags & FLAG_OPEN)) {
 200                 unsigned long size;
 201                 int type = sha1_object_info(obj->oid.hash, &size);
 202                 if (type != obj->type || type <= 0)
 203                         die("object of unexpected type");
 204                 obj->flags |= FLAG_WRITTEN;
 205                 return 0;
 206         }
 207
 208         obj_buf = lookup_object_buffer(obj);
 209         if (!obj_buf)
 210                 die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
 211         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 212                 die("Error in object");
 213         fsck_options.walk = check_object;
 214         if (fsck_walk(obj, NULL, &fsck_options))
 215                 die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
 216         write_cached_object(obj, obj_buf);
 217         return 0;
 218 }
 219
 220 static void write_rest(void)
 221 {
 222         unsigned i;
 223         for (i = 0; i < nr_objects; i++) {
 224                 if (obj_list[i].obj)
 225                         check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 226         }
 227 }
 228
 229 static void added_object(unsigned nr, enum object_type type,
 230                          void *data, unsigned long size);
 231
 232 /*
 233  * Write out nr-th object from the list, now we know the contents
 234  * of it.  Under --strict, this buffers structured objects in-core,
 235  * to be checked at the end.
 236  */
 237 static void write_object(unsigned nr, enum object_type type,
 238                          void *buf, unsigned long size)
 239 {
 240         if (!strict) {
 241                 if (write_object_file(buf, size, type_name(type),
 242                                       &obj_list[nr].oid) < 0)
 243                         die("failed to write object");
 244                 added_object(nr, type, buf, size);
 245                 free(buf);
 246                 obj_list[nr].obj = NULL;
 247         } else if (type == OBJ_BLOB) {
 248                 struct blob *blob;
 249                 if (write_object_file(buf, size, type_name(type),
 250                                       &obj_list[nr].oid) < 0)
 251                         die("failed to write object");
 252                 added_object(nr, type, buf, size);
 253                 free(buf);
 254
 255                 blob = lookup_blob(&obj_list[nr].oid);
 256                 if (blob)
 257                         blob->object.flags |= FLAG_WRITTEN;
 258                 else
 259                         die("invalid blob object");
 260                 obj_list[nr].obj = NULL;
 261         } else {
 262                 struct object *obj;
 263                 int eaten;
 264                 hash_object_file(buf, size, type_name(type), &obj_list[nr].oid);
 265                 added_object(nr, type, buf, size);
 266                 obj = parse_object_buffer(&obj_list[nr].oid, type, size, buf,
 267                                           &eaten);
 268                 if (!obj)
 269                         die("invalid %s", type_name(type));
 270                 add_object_buffer(obj, buf, size);
 271                 obj->flags |= FLAG_OPEN;
 272                 obj_list[nr].obj = obj;
 273         }
 274 }
 275
 276 static void resolve_delta(unsigned nr, enum object_type type,
 277                           void *base, unsigned long base_size,
 278                           void *delta, unsigned long delta_size)
 279 {
 280         void *result;
 281         unsigned long result_size;
 282
 283         result = patch_delta(base, base_size,
 284                              delta, delta_size,
 285                              &result_size);
 286         if (!result)
 287                 die("failed to apply delta");
 288         free(delta);
 289         write_object(nr, type, result, result_size);
 290 }
 291
 292 /*
 293  * We now know the contents of an object (which is nr-th in the pack);
 294  * resolve all the deltified objects that are based on it.
 295  */
 296 static void added_object(unsigned nr, enum object_type type,
 297                          void *data, unsigned long size)
 298 {
 299         struct delta_info **p = &delta_list;
 300         struct delta_info *info;
 301
 302         while ((info = *p) != NULL) {
 303                 if (!oidcmp(&info->base_oid, &obj_list[nr].oid) ||
 304                     info->base_offset == obj_list[nr].offset) {
 305                         *p = info->next;
 306                         p = &delta_list;
 307                         resolve_delta(info->nr, type, data, size,
 308                                       info->delta, info->size);
 309                         free(info);
 310                         continue;
 311                 }
 312                 p = &info->next;
 313         }
 314 }
 315
 316 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 317                                    unsigned nr)
 318 {
 319         void *buf = get_data(size);
 320
 321         if (!dry_run && buf)
 322                 write_object(nr, type, buf, size);
 323         else
 324                 free(buf);
 325 }
 326
 327 static int resolve_against_held(unsigned nr, const struct object_id *base,
 328                                 void *delta_data, unsigned long delta_size)
 329 {
 330         struct object *obj;
 331         struct obj_buffer *obj_buffer;
 332         obj = lookup_object(base->hash);
 333         if (!obj)
 334                 return 0;
 335         obj_buffer = lookup_object_buffer(obj);
 336         if (!obj_buffer)
 337                 return 0;
 338         resolve_delta(nr, obj->type, obj_buffer->buffer,
 339                       obj_buffer->size, delta_data, delta_size);
 340         return 1;
 341 }
 342
 343 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 344                                unsigned nr)
 345 {
 346         void *delta_data, *base;
 347         unsigned long base_size;
 348         struct object_id base_oid;
 349
 350         if (type == OBJ_REF_DELTA) {
 351                 hashcpy(base_oid.hash, fill(the_hash_algo->rawsz));
 352                 use(the_hash_algo->rawsz);
 353                 delta_data = get_data(delta_size);
 354                 if (dry_run || !delta_data) {
 355                         free(delta_data);
 356                         return;
 357                 }
 358                 if (has_object_file(&base_oid))
 359                         ; /* Ok we have this one */
 360                 else if (resolve_against_held(nr, &base_oid,
 361                                               delta_data, delta_size))
 362                         return; /* we are done */
 363                 else {
 364                         /* cannot resolve yet --- queue it */
 365                         oidclr(&obj_list[nr].oid);
 366                         add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
 367                         return;
 368                 }
 369         } else {
 370                 unsigned base_found = 0;
 371                 unsigned char *pack, c;
 372                 off_t base_offset;
 373                 unsigned lo, mid, hi;
 374
 375                 pack = fill(1);
 376                 c = *pack;
 377                 use(1);
 378                 base_offset = c & 127;
 379                 while (c & 128) {
 380                         base_offset += 1;
 381                         if (!base_offset || MSB(base_offset, 7))
 382                                 die("offset value overflow for delta base object");
 383                         pack = fill(1);
 384                         c = *pack;
 385                         use(1);
 386                         base_offset = (base_offset << 7) + (c & 127);
 387                 }
 388                 base_offset = obj_list[nr].offset - base_offset;
 389                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 390                         die("offset value out of bound for delta base object");
 391
 392                 delta_data = get_data(delta_size);
 393                 if (dry_run || !delta_data) {
 394                         free(delta_data);
 395                         return;
 396                 }
 397                 lo = 0;
 398                 hi = nr;
 399                 while (lo < hi) {
 400                         mid = lo + (hi - lo) / 2;
 401                         if (base_offset < obj_list[mid].offset) {
 402                                 hi = mid;
 403                         } else if (base_offset > obj_list[mid].offset) {
 404                                 lo = mid + 1;
 405                         } else {
 406                                 oidcpy(&base_oid, &obj_list[mid].oid);
 407                                 base_found = !is_null_oid(&base_oid);
 408                                 break;
 409                         }
 410                 }
 411                 if (!base_found) {
 412                         /*
 413                          * The delta base object is itself a delta that
 414                          * has not been resolved yet.
 415                          */
 416                         oidclr(&obj_list[nr].oid);
 417                         add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
 418                         return;
 419                 }
 420         }
 421
 422         if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 423                 return;
 424
 425         base = read_sha1_file(base_oid.hash, &type, &base_size);
 426         if (!base) {
 427                 error("failed to read delta-pack base object %s",
 428                       oid_to_hex(&base_oid));
 429                 if (!recover)
 430                         exit(1);
 431                 has_errors = 1;
 432                 return;
 433         }
 434         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 435         free(base);
 436 }
 437
 438 static void unpack_one(unsigned nr)
 439 {
 440         unsigned shift;
 441         unsigned char *pack;
 442         unsigned long size, c;
 443         enum object_type type;
 444
 445         obj_list[nr].offset = consumed_bytes;
 446
 447         pack = fill(1);
 448         c = *pack;
 449         use(1);
 450         type = (c >> 4) & 7;
 451         size = (c & 15);
 452         shift = 4;
 453         while (c & 0x80) {
 454                 pack = fill(1);
 455                 c = *pack;
 456                 use(1);
 457                 size += (c & 0x7f) << shift;
 458                 shift += 7;
 459         }
 460
 461         switch (type) {
 462         case OBJ_COMMIT:
 463         case OBJ_TREE:
 464         case OBJ_BLOB:
 465         case OBJ_TAG:
 466                 unpack_non_delta_entry(type, size, nr);
 467                 return;
 468         case OBJ_REF_DELTA:
 469         case OBJ_OFS_DELTA:
 470                 unpack_delta_entry(type, size, nr);
 471                 return;
 472         default:
 473                 error("bad object type %d", type);
 474                 has_errors = 1;
 475                 if (recover)
 476                         return;
 477                 exit(1);
 478         }
 479 }
 480
 481 static void unpack_all(void)
 482 {
 483         int i;
 484         struct progress *progress = NULL;
 485         struct pack_header *hdr = fill(sizeof(struct pack_header));
 486
 487         nr_objects = ntohl(hdr->hdr_entries);
 488
 489         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 490                 die("bad pack file");
 491         if (!pack_version_ok(hdr->hdr_version))
 492                 die("unknown pack file version %"PRIu32,
 493                         ntohl(hdr->hdr_version));
 494         use(sizeof(struct pack_header));
 495
 496         if (!quiet)
 497                 progress = start_progress(_("Unpacking objects"), nr_objects);
 498         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 499         for (i = 0; i < nr_objects; i++) {
 500                 unpack_one(i);
 501                 display_progress(progress, i + 1);
 502         }
 503         stop_progress(&progress);
 504
 505         if (delta_list)
 506                 die("unresolved deltas left after unpacking");
 507 }
 508
 509 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 510 {
 511         int i;
 512         struct object_id oid;
 513
 514         check_replace_refs = 0;
 515
 516         git_config(git_default_config, NULL);
 517
 518         quiet = !isatty(2);
 519
 520         for (i = 1 ; i < argc; i++) {
 521                 const char *arg = argv[i];
 522
 523                 if (*arg == '-') {
 524                         if (!strcmp(arg, "-n")) {
 525                                 dry_run = 1;
 526                                 continue;
 527                         }
 528                         if (!strcmp(arg, "-q")) {
 529                                 quiet = 1;
 530                                 continue;
 531                         }
 532                         if (!strcmp(arg, "-r")) {
 533                                 recover = 1;
 534                                 continue;
 535                         }
 536                         if (!strcmp(arg, "--strict")) {
 537                                 strict = 1;
 538                                 continue;
 539                         }
 540                         if (skip_prefix(arg, "--strict=", &arg)) {
 541                                 strict = 1;
 542                                 fsck_set_msg_types(&fsck_options, arg);
 543                                 continue;
 544                         }
 545                         if (starts_with(arg, "--pack_header=")) {
 546                                 struct pack_header *hdr;
 547                                 char *c;
 548
 549                                 hdr = (struct pack_header *)buffer;
 550                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 551                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 552                                 if (*c != ',')
 553                                         die("bad %s", arg);
 554                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 555                                 if (*c)
 556                                         die("bad %s", arg);
 557                                 len = sizeof(*hdr);
 558                                 continue;
 559                         }
 560                         if (skip_prefix(arg, "--max-input-size=", &arg)) {
 561                                 max_input_size = strtoumax(arg, NULL, 10);
 562                                 continue;
 563                         }
 564                         usage(unpack_usage);
 565                 }
 566
 567                 /* We don't take any non-flag arguments now.. Maybe some day */
 568                 usage(unpack_usage);
 569         }
 570         the_hash_algo->init_fn(&ctx);
 571         unpack_all();
 572         the_hash_algo->update_fn(&ctx, buffer, offset);
 573         the_hash_algo->final_fn(oid.hash, &ctx);
 574         if (strict)
 575                 write_rest();
 576         if (hashcmp(fill(the_hash_algo->rawsz), oid.hash))
 577                 die("final sha1 did not match");
 578         use(the_hash_algo->rawsz);
 579
 580         /* Write the last part of the buffer to stdout */
 581         while (len) {
 582                 int ret = xwrite(1, buffer + offset, len);
 583                 if (ret <= 0)
 584                         break;
 585                 len -= ret;
 586                 offset += ret;
 587         }
 588
 589         /* All done */
 590         return has_errors;
 591 }