builtin/unpack-objects.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "object.h"
   4 #include "delta.h"
   5 #include "pack.h"
   6 #include "blob.h"
   7 #include "commit.h"
   8 #include "tag.h"
   9 #include "tree.h"
  10 #include "tree-walk.h"
  11 #include "progress.h"
  12 #include "decorate.h"
  13 #include "fsck.h"
  14
  15 static int dry_run, quiet, recover, has_errors, strict;
  16 static const char unpack_usage[] = "git unpack-objects [-n] [-q] [-r] [--strict] < pack-file";
  17
  18 /* We always read in 4kB chunks. */
  19 static unsigned char buffer[4096];
  20 static unsigned int offset, len;
  21 static off_t consumed_bytes;
  22 static git_SHA_CTX ctx;
  23 static struct fsck_options fsck_options = FSCK_OPTIONS_STRICT;
  24
  25 /*
  26  * When running under --strict mode, objects whose reachability are
  27  * suspect are kept in core without getting written in the object
  28  * store.
  29  */
  30 struct obj_buffer {
  31         char *buffer;
  32         unsigned long size;
  33 };
  34
  35 static struct decoration obj_decorate;
  36
  37 static struct obj_buffer *lookup_object_buffer(struct object *base)
  38 {
  39         return lookup_decoration(&obj_decorate, base);
  40 }
  41
  42 static void add_object_buffer(struct object *object, char *buffer, unsigned long size)
  43 {
  44         struct obj_buffer *obj;
  45         obj = xcalloc(1, sizeof(struct obj_buffer));
  46         obj->buffer = buffer;
  47         obj->size = size;
  48         if (add_decoration(&obj_decorate, object, obj))
  49                 die("object %s tried to add buffer twice!", sha1_to_hex(object->sha1));
  50 }
  51
  52 /*
  53  * Make sure at least "min" bytes are available in the buffer, and
  54  * return the pointer to the buffer.
  55  */
  56 static void *fill(int min)
  57 {
  58         if (min <= len)
  59                 return buffer + offset;
  60         if (min > sizeof(buffer))
  61                 die("cannot fill %d bytes", min);
  62         if (offset) {
  63                 git_SHA1_Update(&ctx, buffer, offset);
  64                 memmove(buffer, buffer + offset, len);
  65                 offset = 0;
  66         }
  67         do {
  68                 ssize_t ret = xread(0, buffer + len, sizeof(buffer) - len);
  69                 if (ret <= 0) {
  70                         if (!ret)
  71                                 die("early EOF");
  72                         die_errno("read error on input");
  73                 }
  74                 len += ret;
  75         } while (len < min);
  76         return buffer;
  77 }
  78
  79 static void use(int bytes)
  80 {
  81         if (bytes > len)
  82                 die("used more bytes than were available");
  83         len -= bytes;
  84         offset += bytes;
  85
  86         /* make sure off_t is sufficiently large not to wrap */
  87         if (signed_add_overflows(consumed_bytes, bytes))
  88                 die("pack too large for current definition of off_t");
  89         consumed_bytes += bytes;
  90 }
  91
  92 static void *get_data(unsigned long size)
  93 {
  94         git_zstream stream;
  95         void *buf = xmallocz(size);
  96
  97         memset(&stream, 0, sizeof(stream));
  98
  99         stream.next_out = buf;
 100         stream.avail_out = size;
 101         stream.next_in = fill(1);
 102         stream.avail_in = len;
 103         git_inflate_init(&stream);
 104
 105         for (;;) {
 106                 int ret = git_inflate(&stream, 0);
 107                 use(len - stream.avail_in);
 108                 if (stream.total_out == size && ret == Z_STREAM_END)
 109                         break;
 110                 if (ret != Z_OK) {
 111                         error("inflate returned %d", ret);
 112                         free(buf);
 113                         buf = NULL;
 114                         if (!recover)
 115                                 exit(1);
 116                         has_errors = 1;
 117                         break;
 118                 }
 119                 stream.next_in = fill(1);
 120                 stream.avail_in = len;
 121         }
 122         git_inflate_end(&stream);
 123         return buf;
 124 }
 125
 126 struct delta_info {
 127         unsigned char base_sha1[20];
 128         unsigned nr;
 129         off_t base_offset;
 130         unsigned long size;
 131         void *delta;
 132         struct delta_info *next;
 133 };
 134
 135 static struct delta_info *delta_list;
 136
 137 static void add_delta_to_list(unsigned nr, unsigned const char *base_sha1,
 138                               off_t base_offset,
 139                               void *delta, unsigned long size)
 140 {
 141         struct delta_info *info = xmalloc(sizeof(*info));
 142
 143         hashcpy(info->base_sha1, base_sha1);
 144         info->base_offset = base_offset;
 145         info->size = size;
 146         info->delta = delta;
 147         info->nr = nr;
 148         info->next = delta_list;
 149         delta_list = info;
 150 }
 151
 152 struct obj_info {
 153         off_t offset;
 154         unsigned char sha1[20];
 155         struct object *obj;
 156 };
 157
 158 #define FLAG_OPEN (1u<<20)
 159 #define FLAG_WRITTEN (1u<<21)
 160
 161 static struct obj_info *obj_list;
 162 static unsigned nr_objects;
 163
 164 /*
 165  * Called only from check_object() after it verified this object
 166  * is Ok.
 167  */
 168 static void write_cached_object(struct object *obj, struct obj_buffer *obj_buf)
 169 {
 170         unsigned char sha1[20];
 171
 172         if (write_sha1_file(obj_buf->buffer, obj_buf->size, typename(obj->type), sha1) < 0)
 173                 die("failed to write object %s", sha1_to_hex(obj->sha1));
 174         obj->flags |= FLAG_WRITTEN;
 175 }
 176
 177 /*
 178  * At the very end of the processing, write_rest() scans the objects
 179  * that have reachability requirements and calls this function.
 180  * Verify its reachability and validity recursively and write it out.
 181  */
 182 static int check_object(struct object *obj, int type, void *data, struct fsck_options *options)
 183 {
 184         struct obj_buffer *obj_buf;
 185
 186         if (!obj)
 187                 return 1;
 188
 189         if (obj->flags & FLAG_WRITTEN)
 190                 return 0;
 191
 192         if (type != OBJ_ANY && obj->type != type)
 193                 die("object type mismatch");
 194
 195         if (!(obj->flags & FLAG_OPEN)) {
 196                 unsigned long size;
 197                 int type = sha1_object_info(obj->sha1, &size);
 198                 if (type != obj->type || type <= 0)
 199                         die("object of unexpected type");
 200                 obj->flags |= FLAG_WRITTEN;
 201                 return 0;
 202         }
 203
 204         obj_buf = lookup_object_buffer(obj);
 205         if (!obj_buf)
 206                 die("Whoops! Cannot find object '%s'", sha1_to_hex(obj->sha1));
 207         if (fsck_object(obj, obj_buf->buffer, obj_buf->size, &fsck_options))
 208                 die("Error in object");
 209         fsck_options.walk = check_object;
 210         if (fsck_walk(obj, NULL, &fsck_options))
 211                 die("Error on reachable objects of %s", sha1_to_hex(obj->sha1));
 212         write_cached_object(obj, obj_buf);
 213         return 0;
 214 }
 215
 216 static void write_rest(void)
 217 {
 218         unsigned i;
 219         for (i = 0; i < nr_objects; i++) {
 220                 if (obj_list[i].obj)
 221                         check_object(obj_list[i].obj, OBJ_ANY, NULL, NULL);
 222         }
 223 }
 224
 225 static void added_object(unsigned nr, enum object_type type,
 226                          void *data, unsigned long size);
 227
 228 /*
 229  * Write out nr-th object from the list, now we know the contents
 230  * of it.  Under --strict, this buffers structured objects in-core,
 231  * to be checked at the end.
 232  */
 233 static void write_object(unsigned nr, enum object_type type,
 234                          void *buf, unsigned long size)
 235 {
 236         if (!strict) {
 237                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
 238                         die("failed to write object");
 239                 added_object(nr, type, buf, size);
 240                 free(buf);
 241                 obj_list[nr].obj = NULL;
 242         } else if (type == OBJ_BLOB) {
 243                 struct blob *blob;
 244                 if (write_sha1_file(buf, size, typename(type), obj_list[nr].sha1) < 0)
 245                         die("failed to write object");
 246                 added_object(nr, type, buf, size);
 247                 free(buf);
 248
 249                 blob = lookup_blob(obj_list[nr].sha1);
 250                 if (blob)
 251                         blob->object.flags |= FLAG_WRITTEN;
 252                 else
 253                         die("invalid blob object");
 254                 obj_list[nr].obj = NULL;
 255         } else {
 256                 struct object *obj;
 257                 int eaten;
 258                 hash_sha1_file(buf, size, typename(type), obj_list[nr].sha1);
 259                 added_object(nr, type, buf, size);
 260                 obj = parse_object_buffer(obj_list[nr].sha1, type, size, buf, &eaten);
 261                 if (!obj)
 262                         die("invalid %s", typename(type));
 263                 add_object_buffer(obj, buf, size);
 264                 obj->flags |= FLAG_OPEN;
 265                 obj_list[nr].obj = obj;
 266         }
 267 }
 268
 269 static void resolve_delta(unsigned nr, enum object_type type,
 270                           void *base, unsigned long base_size,
 271                           void *delta, unsigned long delta_size)
 272 {
 273         void *result;
 274         unsigned long result_size;
 275
 276         result = patch_delta(base, base_size,
 277                              delta, delta_size,
 278                              &result_size);
 279         if (!result)
 280                 die("failed to apply delta");
 281         free(delta);
 282         write_object(nr, type, result, result_size);
 283 }
 284
 285 /*
 286  * We now know the contents of an object (which is nr-th in the pack);
 287  * resolve all the deltified objects that are based on it.
 288  */
 289 static void added_object(unsigned nr, enum object_type type,
 290                          void *data, unsigned long size)
 291 {
 292         struct delta_info **p = &delta_list;
 293         struct delta_info *info;
 294
 295         while ((info = *p) != NULL) {
 296                 if (!hashcmp(info->base_sha1, obj_list[nr].sha1) ||
 297                     info->base_offset == obj_list[nr].offset) {
 298                         *p = info->next;
 299                         p = &delta_list;
 300                         resolve_delta(info->nr, type, data, size,
 301                                       info->delta, info->size);
 302                         free(info);
 303                         continue;
 304                 }
 305                 p = &info->next;
 306         }
 307 }
 308
 309 static void unpack_non_delta_entry(enum object_type type, unsigned long size,
 310                                    unsigned nr)
 311 {
 312         void *buf = get_data(size);
 313
 314         if (!dry_run && buf)
 315                 write_object(nr, type, buf, size);
 316         else
 317                 free(buf);
 318 }
 319
 320 static int resolve_against_held(unsigned nr, const unsigned char *base,
 321                                 void *delta_data, unsigned long delta_size)
 322 {
 323         struct object *obj;
 324         struct obj_buffer *obj_buffer;
 325         obj = lookup_object(base);
 326         if (!obj)
 327                 return 0;
 328         obj_buffer = lookup_object_buffer(obj);
 329         if (!obj_buffer)
 330                 return 0;
 331         resolve_delta(nr, obj->type, obj_buffer->buffer,
 332                       obj_buffer->size, delta_data, delta_size);
 333         return 1;
 334 }
 335
 336 static void unpack_delta_entry(enum object_type type, unsigned long delta_size,
 337                                unsigned nr)
 338 {
 339         void *delta_data, *base;
 340         unsigned long base_size;
 341         unsigned char base_sha1[20];
 342
 343         if (type == OBJ_REF_DELTA) {
 344                 hashcpy(base_sha1, fill(20));
 345                 use(20);
 346                 delta_data = get_data(delta_size);
 347                 if (dry_run || !delta_data) {
 348                         free(delta_data);
 349                         return;
 350                 }
 351                 if (has_sha1_file(base_sha1))
 352                         ; /* Ok we have this one */
 353                 else if (resolve_against_held(nr, base_sha1,
 354                                               delta_data, delta_size))
 355                         return; /* we are done */
 356                 else {
 357                         /* cannot resolve yet --- queue it */
 358                         hashcpy(obj_list[nr].sha1, null_sha1);
 359                         add_delta_to_list(nr, base_sha1, 0, delta_data, delta_size);
 360                         return;
 361                 }
 362         } else {
 363                 unsigned base_found = 0;
 364                 unsigned char *pack, c;
 365                 off_t base_offset;
 366                 unsigned lo, mid, hi;
 367
 368                 pack = fill(1);
 369                 c = *pack;
 370                 use(1);
 371                 base_offset = c & 127;
 372                 while (c & 128) {
 373                         base_offset += 1;
 374                         if (!base_offset || MSB(base_offset, 7))
 375                                 die("offset value overflow for delta base object");
 376                         pack = fill(1);
 377                         c = *pack;
 378                         use(1);
 379                         base_offset = (base_offset << 7) + (c & 127);
 380                 }
 381                 base_offset = obj_list[nr].offset - base_offset;
 382                 if (base_offset <= 0 || base_offset >= obj_list[nr].offset)
 383                         die("offset value out of bound for delta base object");
 384
 385                 delta_data = get_data(delta_size);
 386                 if (dry_run || !delta_data) {
 387                         free(delta_data);
 388                         return;
 389                 }
 390                 lo = 0;
 391                 hi = nr;
 392                 while (lo < hi) {
 393                         mid = (lo + hi)/2;
 394                         if (base_offset < obj_list[mid].offset) {
 395                                 hi = mid;
 396                         } else if (base_offset > obj_list[mid].offset) {
 397                                 lo = mid + 1;
 398                         } else {
 399                                 hashcpy(base_sha1, obj_list[mid].sha1);
 400                                 base_found = !is_null_sha1(base_sha1);
 401                                 break;
 402                         }
 403                 }
 404                 if (!base_found) {
 405                         /*
 406                          * The delta base object is itself a delta that
 407                          * has not been resolved yet.
 408                          */
 409                         hashcpy(obj_list[nr].sha1, null_sha1);
 410                         add_delta_to_list(nr, null_sha1, base_offset, delta_data, delta_size);
 411                         return;
 412                 }
 413         }
 414
 415         if (resolve_against_held(nr, base_sha1, delta_data, delta_size))
 416                 return;
 417
 418         base = read_sha1_file(base_sha1, &type, &base_size);
 419         if (!base) {
 420                 error("failed to read delta-pack base object %s",
 421                       sha1_to_hex(base_sha1));
 422                 if (!recover)
 423                         exit(1);
 424                 has_errors = 1;
 425                 return;
 426         }
 427         resolve_delta(nr, type, base, base_size, delta_data, delta_size);
 428         free(base);
 429 }
 430
 431 static void unpack_one(unsigned nr)
 432 {
 433         unsigned shift;
 434         unsigned char *pack;
 435         unsigned long size, c;
 436         enum object_type type;
 437
 438         obj_list[nr].offset = consumed_bytes;
 439
 440         pack = fill(1);
 441         c = *pack;
 442         use(1);
 443         type = (c >> 4) & 7;
 444         size = (c & 15);
 445         shift = 4;
 446         while (c & 0x80) {
 447                 pack = fill(1);
 448                 c = *pack;
 449                 use(1);
 450                 size += (c & 0x7f) << shift;
 451                 shift += 7;
 452         }
 453
 454         switch (type) {
 455         case OBJ_COMMIT:
 456         case OBJ_TREE:
 457         case OBJ_BLOB:
 458         case OBJ_TAG:
 459                 unpack_non_delta_entry(type, size, nr);
 460                 return;
 461         case OBJ_REF_DELTA:
 462         case OBJ_OFS_DELTA:
 463                 unpack_delta_entry(type, size, nr);
 464                 return;
 465         default:
 466                 error("bad object type %d", type);
 467                 has_errors = 1;
 468                 if (recover)
 469                         return;
 470                 exit(1);
 471         }
 472 }
 473
 474 static void unpack_all(void)
 475 {
 476         int i;
 477         struct progress *progress = NULL;
 478         struct pack_header *hdr = fill(sizeof(struct pack_header));
 479
 480         nr_objects = ntohl(hdr->hdr_entries);
 481
 482         if (ntohl(hdr->hdr_signature) != PACK_SIGNATURE)
 483                 die("bad pack file");
 484         if (!pack_version_ok(hdr->hdr_version))
 485                 die("unknown pack file version %"PRIu32,
 486                         ntohl(hdr->hdr_version));
 487         use(sizeof(struct pack_header));
 488
 489         if (!quiet)
 490                 progress = start_progress(_("Unpacking objects"), nr_objects);
 491         obj_list = xcalloc(nr_objects, sizeof(*obj_list));
 492         for (i = 0; i < nr_objects; i++) {
 493                 unpack_one(i);
 494                 display_progress(progress, i + 1);
 495         }
 496         stop_progress(&progress);
 497
 498         if (delta_list)
 499                 die("unresolved deltas left after unpacking");
 500 }
 501
 502 int cmd_unpack_objects(int argc, const char **argv, const char *prefix)
 503 {
 504         int i;
 505         unsigned char sha1[20];
 506
 507         check_replace_refs = 0;
 508
 509         git_config(git_default_config, NULL);
 510
 511         quiet = !isatty(2);
 512
 513         for (i = 1 ; i < argc; i++) {
 514                 const char *arg = argv[i];
 515
 516                 if (*arg == '-') {
 517                         if (!strcmp(arg, "-n")) {
 518                                 dry_run = 1;
 519                                 continue;
 520                         }
 521                         if (!strcmp(arg, "-q")) {
 522                                 quiet = 1;
 523                                 continue;
 524                         }
 525                         if (!strcmp(arg, "-r")) {
 526                                 recover = 1;
 527                                 continue;
 528                         }
 529                         if (!strcmp(arg, "--strict")) {
 530                                 strict = 1;
 531                                 continue;
 532                         }
 533                         if (skip_prefix(arg, "--strict=", &arg)) {
 534                                 strict = 1;
 535                                 fsck_set_msg_types(&fsck_options, arg);
 536                                 continue;
 537                         }
 538                         if (starts_with(arg, "--pack_header=")) {
 539                                 struct pack_header *hdr;
 540                                 char *c;
 541
 542                                 hdr = (struct pack_header *)buffer;
 543                                 hdr->hdr_signature = htonl(PACK_SIGNATURE);
 544                                 hdr->hdr_version = htonl(strtoul(arg + 14, &c, 10));
 545                                 if (*c != ',')
 546                                         die("bad %s", arg);
 547                                 hdr->hdr_entries = htonl(strtoul(c + 1, &c, 10));
 548                                 if (*c)
 549                                         die("bad %s", arg);
 550                                 len = sizeof(*hdr);
 551                                 continue;
 552                         }
 553                         usage(unpack_usage);
 554                 }
 555
 556                 /* We don't take any non-flag arguments now.. Maybe some day */
 557                 usage(unpack_usage);
 558         }
 559         git_SHA1_Init(&ctx);
 560         unpack_all();
 561         git_SHA1_Update(&ctx, buffer, offset);
 562         git_SHA1_Final(sha1, &ctx);
 563         if (strict)
 564                 write_rest();
 565         if (hashcmp(fill(20), sha1))
 566                 die("final sha1 did not match");
 567         use(20);
 568
 569         /* Write the last part of the buffer to stdout */
 570         while (len) {
 571                 int ret = xwrite(1, buffer + offset, len);
 572                 if (ret <= 0)
 573                         break;
 574                 len -= ret;
 575                 offset += ret;
 576         }
 577
 578         /* All done */
 579         return has_errors;
 580 }