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_SHA_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                 git_SHA1_Update(&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_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), oid.hash) < 0)
 176                 die("failed to write object %s", oid_to_hex(&obj->oid));
 177         obj->flags |= FLAG_WRITTEN;
 178 }
 179
 180 /*
 181  * At the very end of the processing, write_rest() scans the objects
 182  * that have reachability requirements and calls this function.
 183  * Verify its reachability and validity recursively and write it out.
 184  */
 185 static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 186 {
 187         struct obj_buffer *obj_buf;
 188
 189         if (!obj)
 190                 return 1;
 191
 192         if (obj->flags & FLAG_WRITTEN)
 193                 return 0;
 194
 195         if (type != OBJ_ANY && obj->type != type)
 196                 die("object type mismatch");
 197
 198         if (!(obj->flags & FLAG_OPEN)) {
 199                 unsigned long size;
 200                 int type = sha1_object_info(obj->oid.hash, &size);
 201                 if (type != obj->type || type <= 0)
 202                         die("object of unexpected type");
 203                 obj->flags |= FLAG_WRITTEN;
 204                 return 0;
 205         }
 206
 207         obj_buf = lookup_object_buffer(obj);
 208         if (!obj_buf)
 209                 die("Whoops! Cannot find object '%s'", oid_to_hex(&obj->oid));
 210         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 211                 die("Error in object");
 212         fsck_options.walk = check_object;
 213         if (fsck_walk(obj, NULL, &fsck_options))
 214                 die("Error on reachable objects of %s", oid_to_hex(&obj->oid));
 215         write_cached_object(obj, obj_buf);
 216         return 0;
 217 }
 218
 219 static void write_rest(void)
 220 {
 221         unsigned i;
 222         for (i = 0; i < nr_objects; i++) {
 223                 if (obj_list[i].obj)
 224                         check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 225         }
 226 }
 227
 228 static void added_object(unsigned nr, enum object_type type,
 229                          void *data, unsigned long size);
 230
 231 /*
 232  * Write out nr-th object from the list, now we know the contents
 233  * of it.  Under --strict, this buffers structured objects in-core,
 234  * to be checked at the end.
 235  */
 236 static void write_object(unsigned nr, enum object_type type,
 237                          void *buf, unsigned long size)
 238 {
 239         if (!strict) {
 240                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].oid.hash) < 0)
 241                         die("failed to write object");
 242                 added_object(nr, type, buf, size);
 243                 free(buf);
 244                 obj_list[nr].obj = NULL;
 245         } else if (type == OBJ_BLOB) {
 246                 struct blob *blob;
 247                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].oid.hash) < 0)
 248                         die("failed to write object");
 249                 added_object(nr, type, buf, size);
 250                 free(buf);
 251
 252                 blob = lookup_blob(&obj_list[nr].oid);
 253                 if (blob)
 254                         blob->object.flags |= FLAG_WRITTEN;
 255                 else
 256                         die("invalid blob object");
 257                 obj_list[nr].obj = NULL;
 258         } else {
 259                 struct object *obj;
 260                 int eaten;
 261                 hash_sha1_file(buf, size, typename(type), obj_list[nr].oid.hash);
 262                 added_object(nr, type, buf, size);
 263                 obj = parse_object_buffer(&obj_list[nr].oid, type, size, buf,
 264                                           &eaten);
 265                 if (!obj)
 266                         die("invalid %s", typename(type));
 267                 add_object_buffer(obj, buf, size);
 268                 obj->flags |= FLAG_OPEN;
 269                 obj_list[nr].obj = obj;
 270         }
 271 }
 272
 273 static void resolve_delta(unsigned nr, enum object_type type,
 274                           void *base, unsigned long base_size,
 275                           void *delta, unsigned long delta_size)
 276 {
 277         void *result;
 278         unsigned long result_size;
 279
 280         result = patch_delta(base, base_size,
 281                              delta, delta_size,
 282                              &result_size);
 283         if (!result)
 284                 die("failed to apply delta");
 285         free(delta);
 286         write_object(nr, type, result, result_size);
 287 }
 288
 289 /*
 290  * We now know the contents of an object (which is nr-th in the pack);
 291  * resolve all the deltified objects that are based on it.
 292  */
 293 static void added_object(unsigned nr, enum object_type type,
 294                          void *data, unsigned long size)
 295 {
 296         struct delta_info **p = &delta_list;
 297         struct delta_info *info;
 298
 299         while ((info = *p) != NULL) {
 300                 if (!oidcmp(&info->base_oid, &obj_list[nr].oid) ||
 301                     info->base_offset == obj_list[nr].offset) {
 302                         *p = info->next;
 303                         p = &delta_list;
 304                         resolve_delta(info->nr, type, data, size,
 305                                       info->delta, info->size);
 306                         free(info);
 307                         continue;
 308                 }
 309                 p = &info->next;
 310         }
 311 }
 312
 313 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 314                                    unsigned nr)
 315 {
 316         void *buf = get_data(size);
 317
 318         if (!dry_run && buf)
 319                 write_object(nr, type, buf, size);
 320         else
 321                 free(buf);
 322 }
 323
 324 static int resolve_against_held(unsigned nr, const struct object_id *base,
 325                                 void *delta_data, unsigned long delta_size)
 326 {
 327         struct object *obj;
 328         struct obj_buffer *obj_buffer;
 329         obj = lookup_object(base->hash);
 330         if (!obj)
 331                 return 0;
 332         obj_buffer = lookup_object_buffer(obj);
 333         if (!obj_buffer)
 334                 return 0;
 335         resolve_delta(nr, obj->type, obj_buffer->buffer,
 336                       obj_buffer->size, delta_data, delta_size);
 337         return 1;
 338 }
 339
 340 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 341                                unsigned nr)
 342 {
 343         void *delta_data, *base;
 344         unsigned long base_size;
 345         struct object_id base_oid;
 346
 347         if (type == OBJ_REF_DELTA) {
 348                 hashcpy(base_oid.hash, fill(GIT_SHA1_RAWSZ));
 349                 use(GIT_SHA1_RAWSZ);
 350                 delta_data = get_data(delta_size);
 351                 if (dry_run || !delta_data) {
 352                         free(delta_data);
 353                         return;
 354                 }
 355                 if (has_object_file(&base_oid))
 356                         ; /* Ok we have this one */
 357                 else if (resolve_against_held(nr, &base_oid,
 358                                               delta_data, delta_size))
 359                         return; /* we are done */
 360                 else {
 361                         /* cannot resolve yet --- queue it */
 362                         oidclr(&obj_list[nr].oid);
 363                         add_delta_to_list(nr, &base_oid, 0, delta_data, delta_size);
 364                         return;
 365                 }
 366         } else {
 367                 unsigned base_found = 0;
 368                 unsigned char *pack, c;
 369                 off_t base_offset;
 370                 unsigned lo, mid, hi;
 371
 372                 pack = fill(1);
 373                 c = *pack;
 374                 use(1);
 375                 base_offset = c & 127;
 376                 while (c & 128) {
 377                         base_offset += 1;
 378                         if (!base_offset || MSB(base_offset, 7))
 379                                 die("offset value overflow for delta base object");
 380                         pack = fill(1);
 381                         c = *pack;
 382                         use(1);
 383                         base_offset = (base_offset << 7) + (c & 127);
 384                 }
 385                 base_offset = obj_list[nr].offset - base_offset;
 386                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 387                         die("offset value out of bound for delta base object");
 388
 389                 delta_data = get_data(delta_size);
 390                 if (dry_run || !delta_data) {
 391                         free(delta_data);
 392                         return;
 393                 }
 394                 lo = 0;
 395                 hi = nr;
 396                 while (lo < hi) {
 397                         mid = (lo + hi)/2;
 398                         if (base_offset < obj_list[mid].offset) {
 399                                 hi = mid;
 400                         } else if (base_offset > obj_list[mid].offset) {
 401                                 lo = mid + 1;
 402                         } else {
 403                                 oidcpy(&base_oid, &obj_list[mid].oid);
 404                                 base_found = !is_null_oid(&base_oid);
 405                                 break;
 406                         }
 407                 }
 408                 if (!base_found) {
 409                         /*
 410                          * The delta base object is itself a delta that
 411                          * has not been resolved yet.
 412                          */
 413                         oidclr(&obj_list[nr].oid);
 414                         add_delta_to_list(nr, &null_oid, base_offset, delta_data, delta_size);
 415                         return;
 416                 }
 417         }
 418
 419         if (resolve_against_held(nr, &base_oid, delta_data, delta_size))
 420                 return;
 421
 422         base = read_sha1_file(base_oid.hash, &type, &base_size);
 423         if (!base) {
 424                 error("failed to read delta-pack base object %s",
 425                       oid_to_hex(&base_oid));
 426                 if (!recover)
 427                         exit(1);
 428                 has_errors = 1;
 429                 return;
 430         }
 431         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 432         free(base);
 433 }
 434
 435 static void unpack_one(unsigned nr)
 436 {
 437         unsigned shift;
 438         unsigned char *pack;
 439         unsigned long size, c;
 440         enum object_type type;
 441
 442         obj_list[nr].offset = consumed_bytes;
 443
 444         pack = fill(1);
 445         c = *pack;
 446         use(1);
 447         type = (c >> 4) & 7;
 448         size = (c & 15);
 449         shift = 4;
 450         while (c & 0x80) {
 451                 pack = fill(1);
 452                 c = *pack;
 453                 use(1);
 454                 size += (c & 0x7f) << shift;
 455                 shift += 7;
 456         }
 457
 458         switch (type) {
 459         case OBJ_COMMIT:
 460         case OBJ_TREE:
 461         case OBJ_BLOB:
 462         case OBJ_TAG:
 463                 unpack_non_delta_entry(type, size, nr);
 464                 return;
 465         case OBJ_REF_DELTA:
 466         case OBJ_OFS_DELTA:
 467                 unpack_delta_entry(type, size, nr);
 468                 return;
 469         default:
 470                 error("bad object type %d", type);
 471                 has_errors = 1;
 472                 if (recover)
 473                         return;
 474                 exit(1);
 475         }
 476 }
 477
 478 static void unpack_all(void)
 479 {
 480         int i;
 481         struct progress *progress = NULL;
 482         struct pack_header *hdr = fill(sizeof(struct pack_header));
 483
 484         nr_objects = ntohl(hdr->hdr_entries);
 485
 486         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 487                 die("bad pack file");
 488         if (!pack_version_ok(hdr->hdr_version))
 489                 die("unknown pack file version %"PRIu32,
 490                         ntohl(hdr->hdr_version));
 491         use(sizeof(struct pack_header));
 492
 493         if (!quiet)
 494                 progress = start_progress(_("Unpacking objects"), nr_objects);
 495         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 496         for (i = 0; i < nr_objects; i++) {
 497                 unpack_one(i);
 498                 display_progress(progress, i + 1);
 499         }
 500         stop_progress(&progress);
 501
 502         if (delta_list)
 503                 die("unresolved deltas left after unpacking");
 504 }
 505
 506 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 507 {
 508         int i;
 509         struct object_id oid;
 510
 511         check_replace_refs = 0;
 512
 513         git_config(git_default_config, NULL);
 514
 515         quiet = !isatty(2);
 516
 517         for (i = 1 ; i < argc; i++) {
 518                 const char *arg = argv[i];
 519
 520                 if (*arg == '-') {
 521                         if (!strcmp(arg, "-n")) {
 522                                 dry_run = 1;
 523                                 continue;
 524                         }
 525                         if (!strcmp(arg, "-q")) {
 526                                 quiet = 1;
 527                                 continue;
 528                         }
 529                         if (!strcmp(arg, "-r")) {
 530                                 recover = 1;
 531                                 continue;
 532                         }
 533                         if (!strcmp(arg, "--strict")) {
 534                                 strict = 1;
 535                                 continue;
 536                         }
 537                         if (skip_prefix(arg, "--strict=", &arg)) {
 538                                 strict = 1;
 539                                 fsck_set_msg_types(&fsck_options, arg);
 540                                 continue;
 541                         }
 542                         if (starts_with(arg, "--pack_header=")) {
 543                                 struct pack_header *hdr;
 544                                 char *c;
 545
 546                                 hdr = (struct pack_header *)buffer;
 547                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 548                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 549                                 if (*c != ',')
 550                                         die("bad %s", arg);
 551                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 552                                 if (*c)
 553                                         die("bad %s", arg);
 554                                 len = sizeof(*hdr);
 555                                 continue;
 556                         }
 557                         if (skip_prefix(arg, "--max-input-size=", &arg)) {
 558                                 max_input_size = strtoumax(arg, NULL, 10);
 559                                 continue;
 560                         }
 561                         usage(unpack_usage);
 562                 }
 563
 564                 /* We don't take any non-flag arguments now.. Maybe some day */
 565                 usage(unpack_usage);
 566         }
 567         git_SHA1_Init(&ctx);
 568         unpack_all();
 569         git_SHA1_Update(&ctx, buffer, offset);
 570         git_SHA1_Final(oid.hash, &ctx);
 571         if (strict)
 572                 write_rest();
 573         if (hashcmp(fill(GIT_SHA1_RAWSZ), oid.hash))
 574                 die("final sha1 did not match");
 575         use(GIT_SHA1_RAWSZ);
 576
 577         /* Write the last part of the buffer to stdout */
 578         while (len) {
 579                 int ret = xwrite(1, buffer + offset, len);
 580                 if (ret <= 0)
 581                         break;
 582                 len -= ret;
 583                 offset += ret;
 584         }
 585
 586         /* All done */
 587         return has_errors;
 588 }