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